Josh Bernstein calls bullshit on bar tipping:
Now let's do some math. Say I spend $40 boozing. Conservatively, that's eight drinks at $4 per—$32. The remaining $8 arises from the obligatory dollar-per-drink tip. Tipping one dollar on a four-dollar drink is akin to a 25-percent gratuity. Throwing a buck on a $2 PBR, why, that's 50 percent. Hookers aren't tipped that well. [New York Press]
Bernstein goes on to suggest a sliding scale for tips: at least a whole dollar for mixed drinks, a buck for two out of every three rounds of draft beer, and nothing for beer in a can.
Well, I call bullshit on Bernstein. If you can afford to drink in a bar, you can afford to tip at least a dollar per drink.
Why should the tip depend entirely on the relative difficulty of serving a particular beverage? Whatever you're drinking, you're tipping for the whole package: taking the order, getting it right, bringing it out, juggling competing demands to keep service running smoothly, being friendly, and so on.