"If you leave no tip at all, in a place where there is no built-in 15%, and you do so because of poor service, I think that's just as douchey a move as a waiter giving you that poor service to begin with. " You've got to be kidding. I would never leave a tip for bad service. I would write a note instead telling them why I didn't just in case they didn't get the message. Or maybe just a nickle to get the point across.