For many people, the upcoming holiday season also is the drinking season. But be careful not to get taken when you order drinks—dishonest bartenders, bar owners and restaurant owners might attempt to serve you less drink than you paid for. I believe this happens at perhaps 10% to 15% of bars, including restaurant bars.

Experienced drinkers tend to assume that they can spot a watered-down or over-iced drink, but sneaky bartenders and establishments have ways to disguise these tricks, and they have come up with various other tricks to cheat customers.

Here are six warning signs that you might be served a less-than-honest libation or targeted with some other bartender trick…

Warning sign: Crushed ice or tiny ice cubes. Putting an excessive amount of ice in a glass is one of the oldest tricks in the book—lots of ice leaves less room for liquor. But drinkers tend to notice and complain if they see that ice virtually fills a glass.

What many drinkers don’t realize is that bars have a way to get excessive amounts of ice into a glass without appearing to give you a diluted drink—they use crushed ice or tiny ice cubes. These pack together so tightly that there can be a tremendous amount of ice in the glass and yet that ice reaches no higher than normal.

What to do: Before ordering your drink, glance around at other patrons’ glasses to see what type of ice the bar is using. If you see crushed ice or tiny cubes, consider ordering a drink that is not on the rocks…or asking for your ice in a separate glass.

Of course, it’s possible you could get an honest pour even at a bar that uses crushed ice. To know for sure, count off the seconds it takes for the bartender to pour liquor into patrons’ glasses. An honest 1.5-ounce pour of liquor should take three to four seconds. If it seems quicker, ask, “Do you give a one-ounce pour here or a 1.5-ounce pour?”

If the answer is one ounce, you are getting less liquor than normal for your money. If nothing else, asking this question sends a strong message to the bartender that you’re a savvy customer who doesn’t want a weak drink.

Warning sign: The bartender puts on a “long pour” show. If the bartender holds liquor bottles high up in the air as he/she pours, creating a long stream of liquid in the air, he might be showing off his bartending skills…or he might be pulling a psychological trick on his customers. When people see this long stream of liquor, they tend to assume that they are getting lots of it. But bartenders sometimes do “long pours” that also are quick pours.

What to do: Silently count off the duration of the long pour. If it lasts less than three to four seconds, it’s very possible that patrons are not getting a full 1.5 ounces despite the height of the bottle.

Warning sign: Straws come from a spot below the bar that you cannot see. In this case, there’s a chance the bartender is trying to trick patrons’ senses so that they don’t notice watered-down drinks. The hidden straws might be soaking in a glass of vodka (or some other high-proof alcohol). That way, when patrons lift their glasses and/or touch their straws to their lips for the first time, they get a strong initial smell and taste of alcohol.

Some bartenders even press a finger tightly over the top of a straw that’s standing in vodka and then carefully transfer the straw to a patron’s glass with the vodka still inside so that the first sip taken through the straw is extremely alcoholic. First impressions are lasting impressions with drinks, as with people, so this can convince a drinker that a very weak drink actually is a strong one.

What to do: Be suspicious if bartenders retrieve straws from a spot that’s out of sight…especially if you see the bartender’s finger pressed on top of straws as they go into glasses. Also, be wary if glasses are stored out of sight below the bar or disappear under the bar for a moment before drinks are served. Sometimes the rim of the glass, rather than the straw, is dipped in vodka.

Warning sign: The bartender does not enter each transaction into the register…or you see him ring up an amount lower than what you paid for a drink. You can probably figure out what’s happening here—the bartender is pocketing money, stealing from his employer. What you might not realize is that this could mean you are being cheated, too.

Most bar and restaurant owners try to keep their bartenders honest by carefully comparing the amount of liquor that the bar goes through with the liquor sales that are rung up. Bartenders know this, so to get away with shorting the register, they often short drinks, too—a bartender who pockets the cash from every third liquor sale, for example, might put one-third less liquor in each drink.

What to do: If you notice a bartender not ringing up sales or underringing sales, watch especially carefully for the drink-preparation tricks described earlier. Consider ordering bottled beer to avoid underpours. Or better yet, drink elsewhere.

Warning sign: Top-shelf” liquor bottles have worn-looking labels. Some bar owners refill empty bottles of expensive liquor with cheaper substitutes. They know that many drinkers won’t be able to tell the difference.

It’s a bad sign if the labels on one or more top-shelf liquor bottles appear to be old, worn or peeling. That rarely happens during the normal life of a liquor bottle and could mean that these bottles have been refilled, perhaps ­multiple times.

What to do: Don’t pay up for pricey top-shelf liquor if any of the top-shelf bottle labels look worn unless you know and trust the bar or restaurant. Be especially wary about ordering top-shelf vodka and rum—these are especially likely to be replaced with cheaper substitutes because vodka and rum often are combined with juices or other mixers that largely hide their quality…and, in the case of vodka, because few drinkers can tell expensive vodka from cheaper stuff.

Warning sign: The bartender calls a cab for you. In this era of smartphones and car services such as Uber and Lyft, unless you literally are too drunk to arrange for your own ride, there’s no reason for a bartender to call a cab for you. He might not just be doing you a favor—he might be getting a kickback from the cabdriver who might end up overcharging you to recoup this cost.

What to do: Don’t drive if you’ve had more than two drinks, but arrange your own ride unless you know and trust the bartender.

Three Ways to Avoid Bar Germs

What’s worse than getting taken by a less-than-honest bar? Taking ill after drinking at an unhygienic one. Many bars (and even restaurant bar areas) have far lower sanitary standards than restaurant kitchens, opening the door to illness. To stay safe…

Check the cutting board behind the bar. These cutting boards typically are made of white plastic. If you see significant discoloration, do not order any drink that includes sliced fruit such as a lime or lemon wedge. The discoloration could be the result of a bacterial contamination.

Skip the cherry. Bartenders tend to take maraschino cherries from a big jar that is kept behind the bar. Although new cherries likely are added to this jar regularly, the juice these cherries sit in might not have been changed in months or even years.

Watch how the bartender holds glasses. If you see the bartender touch the rims or interiors of other customers’ glasses, order a bottled beer, which does not require a glass…or walk to the other end of the bar and order from a different bartender.