A couple weeks ago I went with a friend of mine to an "organic vegetarian restaurant." This was definitely my first mistake of the day. The second came when I ordered a glass of red wine. I figured if I was going to eat healthy, why not chase it down with some good old alcohol- just to balance out the experience. I took a sip of the "organic" wine, and immediately cringed. It tasted awful. I gave my friend a sip, and she agreed that it had gone bad.

Up to that date, I had never returned a glass or bottle of wine. Being unsure of whether a wine has definitely turned, I've never wanted to be "that guy." You know the one- he takes a sip, then returns the bottle to show those around him how cool and sophisticated he is. Anyway, I was pretty confident on this one. I called over the overly tattooed and dread-locked waitress, and let her know. She confirmed that the bottle had gone bad.

The experience at this restaurant got me thinking more and more about how an unsophisticated wine drinker like myself could identify if a wine has turned. I've searched the web, and found this awesome article by a guy named Jim Gordon. I've pasted the text below. It's a little long and wordy, but it's a great summary of why a wine turns, and how to identity it. I've bold-ed some of the key points to make it easier to get through.

How to...Know when a good wine has gone bad

by Jim Gordon

Here's how to know the difference between a wine that just doesn't suit you and one that should be poured down the drain.

Corked

The most common flaw in wine comes from a defective cork that infects the wine and turns the aroma to a mildewed, wet-cardboard smell and the taste to a flattened, dried out sensation. The wine is called "corked" or "corky."

Oxidized

The oxygen in air makes a good wine go bad in a day or two if an opened bottle isn't properly looked after. An oxidized wine smells to me like stale bread or weak vinegar. This a particular hazard with wines by the glass at restaurants, where half-empty bottles are often kept on the bar overnight. Refrigeration helps, even for reds.

Cooked

Wine can be "cooked" if kept in hot attics or trunks, above stoves or in frugally minded corporate offices where the AC is turned off over the weekends. It's a slow simmer, but the wine gets ruined before long. It will look brownish around the edges of the glass (whether red or white) and may smell caramelized. If you also noticed that the cork in the bottle was pushed up and partway out, it's probably cooked.

Going through malolactic

Winemakers put most red wines and many whites, especially Chardonnay, through a mild secondary transformation in addition to the yeast fermentation that turns them from grape juice into wine. the conversion is called malolactic. But if a winemaker isn't careful, the malolactic can happen after wine is bottled. The result can vary from a mild effervescence to a totally stinky aroma and bizarre flavors. One frequent sign is an unusually cloudy or hazy appearance.

Sulfury

Sulfur dioxide is added to virtually all wines in very small quantities to prevent oxidation and bacterial growth. That's why you see the note on the label that says "Contains Sulfides." Sulfur is a good thing in moderation, but if the winemaker goofs and adds too much, then the wine smells like matchsticks and can prickle the inside of your nostrils. It's not wise to drink it. Another wrinkle on the sulfur problem is when a wine smells like rotten eggs.