Originally Posted by Requiem
The amount I tip completely depends on the service I am receiving.
This is absolutely the way to go.
I've tended bars and served at many different restaurants and the concept of a flat, mandatory tip seems insane to me. It would be awesome for the servers, but it's ridiculous. Nothing made me madder as a server than to work with some lazy, careless slacker who was making as much or more than I was while I busted my ass for the customer.
Honestly, even the 15% thing is pretty absurd to me. A guy who sells a bowl of soup and a soda, then provides countless refills and crackers, etc shouldn't automatically be tipped less than a dude who sells a fancy filet and then just walks away.