I always tip anyone who relies on tips for a living. I think sometimes we think too much about whether the server is being overtipped. I refuse to look at it that way. If I were drinking at an open bar, I would tip what I always tip - because I can afford to, it’s a nice thing to do, and most importantly, because the person serving deserves to be paid for his or her work. If the bartender ends up with twice as much somehow, why should that bother me? A few drinks for a few bucks is a great deal. Enjoy it. If the bartender goes home with a few extra bucks, that’s even better if you ask me.