Ok lets go with the OP's original question and decide not to tip at all you go out and grab a bite to eat at a restaurant and the waiter wasn't anything special not bad but not worth tipping either.. then what? The restaurant picks up the slack they make up for the lack of tips that each server gets by probably raising the price of the food on the menu. I guess what I'm saying is that while it is customary to tip and maybe a decent restaurant would "suggest" a 10% gratuity then its really up to you if you tip or dont. Either way you're the one going out for a good time and spending $6-$10 on a burger anyways then you might as well tip the server while you're spending money for going out. To not tip I guess in my mind would be like getting all dressed up for a night out at a club and not drinking at all once you got there.
The OP brings up a good point, I tip at any restaurant I go to, but to be honest, it is mainly because it is just what I have grown into. It is always about 20%, and it is never because of exceptional service or anything.
Another place where you always see tipping cups and the sort are ice-cream places and coffee shops. Granted, coffee shops can have some pretty precise orders that somebody may tip for, but I never tip anything more than what I get in pennies for change at places like this. I never order anything ultra-specific, so I never feel the need to tip. And I only tip the pennies because pennies for me never accumulate to much of anything, they just jingle around in my pocket and annoy me. But one time that I do tip at places like this are when somebody stays at the window to serve you well after the posted closing time. Whenever I do this, I always tip a few bucks, after all, they did stay there longer to serve me than what they were getting paid for.
Another time when I hate tipping is included gratuity tips, what if the service was horrible, why should I be required to tip?