4 Ways a Bartender Can Rip You Off, and What You Should Order And what drinks you should actually order at the bar.

Nov. 21, 2013 -- intro: People head to their local watering holes to let loose, blow off steam, knock a few back, get their drink on, but you might want to think twice before paying $10 for that second vodka-cranberry.

Because whoever has the alcohol is in control, and the man behind the bar could be ripping you off.

Jon Taffer, who has started, flipped or owned more than 600 bars and clubs during his career, is the host of Spike TV's "Bar Rescue." He crisscrosses the country, helping to turn struggling bars back into booming businesses. In an interview with "20/20," Taffer said the sad truth is that some bars mess with everybody, not just the rowdy drunks.

"In the bar business, sometimes people are losing so much money. They can be losing $10,000 to $20,000 a month. Their house is on the line. They get desperate," he said.

Some bartenders have tricks they use to cheat customers, Taffer said, from pouring less than the full amount of liquor you were charged for to watering down drinks and even secretly giving you a cheaper brand than you ordered. While most bartenders are honest and don't employ these tricks, there is a small minority that do.

So what makes you an easy target?

It can come down to what and how you order. Most people have trouble telling the difference between top-shelf vodka and the cheap stuff, Taffer said, so bartenders might try to charge you for the Grey Goose you wanted, but pour you a glass of something more like Nikolai.

"If you come and say 'Let me have a Johnnie Walker Black on the rocks,' I'm not going to mess with that. I'm giving you Johnnie Walker Black," he said. "If you come up to me and say 'Let me have a Grey Goose and orange juice,' that's the ticket to pour you the cheapest vodka I've ever had."

Here are a few ways Taffer says cheating bartenders can rip you off, and why you should re-think your order.

quicklist:1 title: Swapping Good Booze for a Cheaper Brand or Even Water media: 20950067 text: Sometimes bartenders will pour cheap liquor into an empty premium bottle, Taffer said, or they'll add water to a half-finished top-shelf brand.

"Either you're getting diluted [liquor] or you're getting a different brand altogether," he said. "It's the epitome of desperation. It's stupidity."

It could be the bartender doing the switcheroo on his own, or the owner telling the bartender to be dishonest, or both, Taffer said. In the end, those who do it do so to try to make more money off each drink.

"Let's say drinks are $10 each. ... I put 10 ounces of water in [a] bottle," Taffer said. "I just made myself $100 dollars, and I'm going to leave with that in cash tonight. ... Times that by working 20 days a month, and by the year, it becomes very profitable."

quicklist:2 title: Giving You the 'Short Pour' media:15920699 text: Crushed ice, meaning the ice that comes out of those large bins behind the bar, means less liquor, Taffer said, while cubed ice allows for more space for liquor and is a better deal. But a half jigger of booze poured over crushed ice appears to look like more booze than a full jigger poured over cubed ice, he said.

It's called a "short pour," Taffer said, because "I'm going to charge you for a full drink and give you about half a drink. ... You won't know it. I'm going to rip you off and you're going to be happy the entire time."

quicklist:3 title: Giving You the 'Long Pour' media: 20951080 text: Don't be impressed if your bartender can pour a drink a foot away from the glass, Taffer said. He is just cheating you out of booze by creating an illusion.

"This idea is holding the arm up high in an exaggerated pouring motion, you think you are getting special treatment, you are only getting a special show. No extra booze, maybe even less," he said. "When you lift that arm, you create an illusion of quantity. ... Not only are you not special, you're the exact opposite. I'm ripping you off."

quicklist:4 title: Giving You the 'Sneaky Pour' media: 20942916 text: When a bartender holds the bottle over your glass for a long time, he is obviously giving you something extra, right?

Wrong, says Taffer, but you'll tip him as if he did.

"The truth is they hold their finger over the air hole on the spout, which reduces the flow to a trickle," he said. "They hold the bottle instead of the glass so you can't see how little is flowing out. ... Then they quickly add the mixer and plop in that straw."

That little red straw is the key to fooling you into thinking that weak drink the bartender just gave you tastes strong because, Taffer said, unscrupulous bartenders will keep those straws in a glass of vodka hidden under the bar.

"The bartender draws a swig out of that vodka and your first sip tastes strong," he said. "You are convinced, even though the rest of the drink is weak."

quicklist:5 media: 20943010 title: BONUS: Want to Avoid Being Messed With? Order Bottled Beer text: The only thing the bartender can't tamper with in a bar, Taffer said, is bottled beer.

"Unfortunately bottled beer is your safest bet," he said. "It's prepackaged. It's sealed. You see it opened in front of you."