My usual approach to any spending decision – any time that money leaves my checking account – is to make sure I’m getting the most value for the dollar. Almost every time, I’m happy with the overall outcome. I got the result I desired with close to minimal expense.

There are times, though, when things don’t go quite as planned. Sometimes, I’ll find that a seeming bargain isn’t an actual bargain.

Here are 14 examples of situations over the last few years where I believed I was operating in a frugally sensible manner, only to have the situation backfire badly. In each case, I learned a lesson and was able to hone my frugal sensibilities a bit better going forward.

Failure #1: Letting Frugality Harm a Relationship

I used to go out to lunch occasionally with a married couple that I knew from my college years. They always wanted to go to really expensive places for lunch, so I started suggesting cheaper places. At first, they went a few times, but then they started declining my invites and not offering any in return.

I later found out that these friends thought I was trying to impolitely avoid them. They wanted to have some classy long lunches with an old friend, whereas I kept insisting on cheap ethnic places where the meal would be done in 20 minutes. They felt I was trying to get meals done quickly and get away from them and was only doing it out of obligation.

The mistake I made here was looking exclusively at the price rather than the big picture. Often, when someone invites you out to eat, they’re doing it because they want a nice social experience with you, not because they want the cheapest decent meal out there.

Luckily, I was able to repair the friendship and we still go out to eat every once in a while, usually at a place where it’s pleasant to linger and converse for a while.

Lesson learned: A meal with an old friend might have more meaning than simply the least expensive decent meal in town, so if it’s done irregularly, don’t be afraid to go somewhere nice for an occasional meal with a good friend. Also, be sure you’re communicating well with old friends, as that will often resolve a lot of issues right away.

Read more: Friendships and the Financial Turnaround

Failure #2: Buying Cheap Tires

The tires on my wife’s car were getting thin. A friend suggested that we buy some really good used tires from a place he recommended and, at first glance, the tires seemed great for the price. They weren’t the type I usually buy, but the price seemed really good and the wear seemed minimal, so we went with them.

There were a few problems, though. One, the tires caused a significant change in fuel efficiency. My wife was suddenly fueling up more frequently than before and her car noted a roughly 10% drop in fuel efficiency due to greater tire contact with the road. Two, the tires seemed to wear down extremely fast, causing us to have to replace them faster than we ever expected. Three, they didn’t handle very well at all in wintry conditions.

We went back to our preferred tires and the fuel efficiency rebounded to previous levels and the car’s handling in winter weather improved drastically. The price per mile on the good tires is already less than those off-brand used ones and we’re not even counting the fuel savings.

Lesson learned: “Too good to be true” prices are often just that. There’s nothing wrong with trying out a new product, especially if the price is good, but be wary, especially when it’s a product you really rely on. I’m probably not buying cheap tires again – tires fall into a class of “stick with something you trust that works well” because they’re relied upon so heavily.

Failure #3: Overinvesting in a Hobby

I really enjoy home brewing as a hobby, but I mostly do it roughly at cost. Let me explain. I have a handful of equipment for home brewing that I received as gifts over the years and I’ll occasionally make a batch of home-brewed craft beer that ends up costing about as much as buying a similar craft beer at the store (maybe a bit less, depending on what I’m making).

A few years ago, I went through a phase where I was really into it. I made a bunch of batches in a single year, went to some local meetings, traded some bottles with other home brewers, gave away six packs as gifts, provided home-brewed beer for a party, and so on.

During that phase, I decided to start scaling up my gear. I ended up spending money on a few items that really pay off if you’re home brewing frequently, but aren’t really necessary if you’re only making one batch every few months.

Well, I still participate in the hobby, but my frequency has declined back to earlier levels. To make matters worse, I only bought some of the equipment needed to “gear up” to a higher throughput, so my entire process now is a little weird, involving me having to move my batches back and forth between two different areas in my home.

Lesson learned: There’s nothing wrong with investing in a hobby, but make sure it’s something you’re deeply passionate about and ready to take to another level. Think through that move thoroughly first and don’t put yourself in a position where things actually work worse than before because you didn’t think through your upgrades. I should have waited and fully planned out the upgrades and really considered whether they were necessary instead of buying random copper piping without a better plan.

Read more: 12 Enjoyable Hobbies That Can Actually Save You Money

Failure #4: Buying Cheap Walking Shoes

I bought a pair of very inexpensive shoes mostly meant for walking around our neighborhood. They seemed to fit well and had decent but not spectacular reviews online, but the price seemed good.

Within a week, I was hobbling around with foot pain and some back pain from the awkward walk I had adopted. My feet were killing me and so I went back to my old shoes temporarily. The pain abated quickly, even though those old shoes were falling apart.

Rather than giving it another try, I just bought a replacement pair of the same “good” shoes that were falling apart. They cost about three times as much, but they work much better. It turns out that a good pair of New Balance walking shoes is far better than the cheap-o special.

Lesson learned: If you rely on something every single day to keep pain and discomfort at bay, be very careful and thoughtful with that purchase and don’t be afraid to move on quickly if you find yourself in pain or discomfort. Shoes definitely fall into this category, especially if you walk or run a lot.

Failure #5: Freebie Pen Failure

I was at a community event where someone was handing out free pens. I grabbed one, stuck it in my pocket, and used it a couple of times during that day. Sweet! A free pen!

By evening, the pen tip had bent, causing the blue ink to rush out of the pen and all over my clothes, ruining them. I had to toss one of my favorite shirts.

There’s nothing wrong with having a free pen in a drawer somewhere to sign a piece of paper or fill out a quick form, but don’t carry it around with you. You’ll regret it.

Lesson learned: Don’t keep a cheap pen in your pocket. Even if it’s free, the potential cost just isn’t worth it. If you write a lot, spend $0.80 and get a decent clickable pen or a pen with a good cap and a sturdy body to carry with you. I’m sticking with my Uniball Signos going forward.

Failure #6: Leaving Leftovers Behind

I’m very diligent about putting aside leftovers for the future. After dinner, I’ll package up what’s left behind into individual meal containers or some other method of storage that’s likely to be useful.

Where I often fall short is remembering to eat those leftovers – or, sometimes, when I do think about them, actually eating them.

The end result is that sometimes leftovers are found in the fridge and they’re far past when they should be used. They have to be dumped out, and that’s just wasted food (and thus wasted money).

There’s really a twofold problem here. One is remembering the leftovers, and two is making the leftovers appealing.

Lesson learned: To make sure I remember leftovers, I stick a reminder in my phone for 11 AM on the day I think I’ll eat those leftovers. It pops up reminding me of the leftovers that are waiting for me, so I don’t have to think about it. I can just eat. To make sure leftovers are appealing, I’ve started adding a little extra seasoning or some other ingredient to gently remix the leftovers. If I have leftover curry, I’ll add a bit of extra sauce or curry powder. If I have leftover spaghetti, I’ll add a bit of shredded mozzarella. It’s really easy to do this kind of tweak and it makes leftovers far more interesting.

Read more: 10 Smart Ways to Use Leftover Rice

Failure #7: Don’t Lowball a Contractor

I’m still going to call this a failure, even though it was honestly a failure that was narrowly averted.

Recently, we had some work done on our home that was a bit outside of our skill level. We decided to contract out the work and so we got several bids for the job.

My natural instinct was to go for the lowest bid. The person seemed pleasant enough and the bid wasn’t absurdly low compared to the others.

Just as we were about to say yes, I asked my social network for feedback on a number of contractors and got a note from two different and unrelated people telling me that this person did shoddy work – not intentionally bad, but just shoddy and not well-finished or professional.

I was literally ready to sign the papers within 24 hours when I got that update. Due to the suggestions of other friends, we ended up going with a somewhat more expensive contractor (about 25% more) who did a fantastic job.

Lesson learned: Don’t hire the cheapest contractor just because that contractor is cheap. It’s okay to be price conscious, but choose a contractor with a good reputation. The cost of a contracted job going bad will blow away whatever you saved by going with the cheapest option. Trust your social network and their recommendations.

Failure #8: Overbuying cheap supplies

I found a great deal on blank notebooks a few years ago. They were the exact kind I like the best and were selling for about 20% of the price that they normally sell for. They were legitimate, too – I was able to inspect them before buying.

I bought them all without skipping a beat. It was a great bargain, except…

I write in my notebooks a lot, but four years later and I still have shelves of these notebooks. I’ve sold some of them and used a ton of them and I still have a lot of these notebooks sitting around. I probably have a lifetime supply of these notebooks, and they just take up space.

Lesson learned: There’s nothing wrong with buying an item in bulk that you’re sure you’re going to use, especially when it’s at a discount, but there is an upper limit to this. Don’t buy so much of an item that it’s likely to exceed your natural life because you will have to deal with storing it.

Read more: The Ginger Principle: When Buying in Bulk is a Mistake

Failure #9: Frugal Repair Mistakes

Several years ago (this is probably the earliest “mistake” in this article), I tried replacing a toilet. Everything was fine except that when I removed the toilet, I accidentally bent the water valve without noticing it, so when I turned the water back on, there was a pretty steady leak. I had no idea what to do next, so I spent an hour looking through a DIY book that I had and eventually figured out how to fix it, but I ended up turning a 30-minute job into several hours of confusion, a number of additional parts, and a ton of additional cleanup.

If I had simply prepared ahead of time and read all of the caveats of the procedure in the DIY book to begin with, I would have saved myself a ton of time.

Lesson learned: If you’re trying a new home improvement project, make sure you read through the procedure first and watch lots of videos. Also, make sure you know how to handle things that might go wrong. For example, if you’re doing something with the water, make sure you know how to turn off water in the room and for the whole apartment or home. If you’re doing something with electricity, make sure you know how to turn off the breaker for that area.

Failure #10: Understanding Your Home’s Wiring

This one’s comically easy to avoid, but still worth noting here.

We had some improvements done to our home recently and part of those changes involved a small amount of rewiring, for which we hired an electrician for a day’s work. What we didn’t understand at the time was that there was now a new GFCI breaker installed in an outlet, but that outlet was on a circuit that included our deep freezer.

We accidentally tripped this breaker and so we went out to the breaker box and couldn’t find any breakers that had been flipped. Our conclusion? Something must have been wired wrong.

We call the electrician, who isn’t sure what’s going on but agrees to stop by and check.

Life goes on. Two days later, my wife notices that our deep freezer is “broken.” This arouses further suspicion that something is going on with the breakers and I go out and check them again. I then literally start investigating every single bit of new wiring done for the project and eventually discover the GFCI breaker, which wasn’t there before. A single button push and suddenly the new outlet is working, as is the deep freezer.

We lost some food and almost lost money spent on calling in an electrician simply because we weren’t aware of the basic functions of our home.

Lesson learned: Know the electrical wiring of your home. Know where the breakers are (including the outlet breakers), the water valves, and so on. Knowing those things can save you a lot of money and stress – and possibly keep you from losing a lot of food.

Failure #11: Making Things Yourself Without Figuring Out the Full Cost

There are a lot of things that are much cheaper to make at home than to buy elsewhere. Most family dinners, for example, are far cheaper to make at home. Coffee (provided you buy roasted beans) is much cheaper to make at home. Naturally, knowing this can cause a person to start defaulting to making as many things at home as possible.

The catch, of course, is that there are a lot of things that aren’t cheaper to make at home.

Sarah was frustrated in October with the lack of interesting Halloween costumes available for our children and decided to make a couple from scratch. After investing roughly 50 hours worth of effort along with several trips to a craft store and a fabric store, she ended up spending more on materials than a similar costume in the store (though hers did look better) and invested many, many hours in the costume.

About halfway through the process, she regretted it, not because she didn’t enjoy making the costume, but because it ended up being a time and money investment far beyond simply purchasing a basic costume.

This isn’t the first time this has happened. I’ve made many food items that ended up costing far more than just buying them at the store (often because I had to make a larger volume than necessary or else things would go to waste). My experiments with preserved lemons come to mind.

Lesson learned: Unless you’re doing something strictly for fun or learning, make sure you’re doing the math beforehand when making something at home. It can often end up costing more than just buying the item at the store.

Failure #12: A Good Price Isn’t Enough

Just because something is available at a stellar price doesn’t mean you should buy it immediately, even if you think you might flip it or you think you might use it. Save your money for stuff you will use or that you will flip immediately.

A while back, I bought a bunch of items at a kitchen supply store as it was going out of business. The prices were stellar and I thought I’d end up using some of the stuff and flipping some of the other stuff.

I ended up putting about three items in our kitchen. I then sat aside the other items in a box that wound up in our garage.

I found this box just a few days ago. The items in it were bought three or four years ago and just sat there since. A few of them aren’t usable any more (I think temperature change affected them). I might use one or two of the remaining things. I can still flip some of the others, and I might recoup the cost.

What a waste of money.

Lesson learned: Don’t buy things just because they’re on sale or the price is great. Do you actually need this item? Do you have the capacity to extremely quickly flip this item and earn a tidy profit for your effort – meaning, do you have the time to do this and know how to instantly find someone to buy it? If you can’t say a strong “yes” to one of these things, then you shouldn’t be buying the item.

Failure #13: Buying Cheap Replacements for Daily Use Items

We store a lot of food. We do meal prepping, which means we prepare full meals in advance and store them in the freezer. We save leftovers virtually every night. We often put aside ingredients for future meals, like chopped vegetables.

For a lot of this stuff, we’ve always used cheap containers that don’t stand up to a lot of repeated use. In with those cheap containers, we have a handful of nicer containers we’ve picked up here or there that stand up to a lot of use.

I recently ran the numbers and I found that the cost per use of the expensive storage containers (Pyrex) was less than the cost per use of some of the cheaper containers that we wound up tossing. In fact, it wasn’t even close.

We’re not buying the cheap containers any more.

Lesson learned: If you use something daily (or close to it), make absolutely sure that what you’re using gives the best value per use, not the lowest price. If you’re not sure, go for the sturdy and reliable version because you’ll be able to invest less time in shopping for replacements later on.

Failure #14: Rebates

As I was clearing out my office, I came across a rebate form and a receipt for our home printer. Great! I can send it in for cash, right?

The rebate expired in 2016.

Rebates seem like a great thing, but if you don’t do them immediately, they quickly lose their urgency and are forgotten. That’s often why manufacturers offer rebates in the first place – they get forgotten or overlooked by the customer, so the manufacturer never has to pay out.

Lesson learned: Unless you are going to fill out a rebate immediately, just ignore it. If you’re not going to fill it out immediately, then it’s very likely that you’ll never fill it out and it ends up being wasted money.

Final Thoughts

Frugality is not a perfect science. It’s just as fallible as anything else we do in life. It’s failed by forgetfulness. It’s failed by a lack of preparation. It’s failed by laziness.

The key thing, always, is to look at those situations where things go wrong and ask yourself what you could have / should have done differently. That way, you can take that lesson with you and apply it the next time around.

Good luck!

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