Customer's complaints are usually taken very seriously here, and while they might not instantly cause troubles to the servers, you usually get compensated if you say something wasn't right with the food/service was bad.
Servers are just too replaceable. It's not worth risking a bad reputation because of it.
On the other side, the owner of one of the independent restaurants I worked for threw people out of his restaurant once or twice for being rude to the servers and other employees. We had an open kitchen which allowed people to talk to the chef(he was the owner), so if customers bothered him with something,t hey had better be able to prove it.
Unless you're referring to a repeat customer who always comes in and never tips, in that case I believe that person will not get the same service from most people.
If I do I know the person serving me is pretty much working for my tip not their salary so much.
I take that into consideration and as long as I feel they did their job (which is pretty much be around if I need something and to fill my drink before its empty) I will tip them and I expect to be doing this. However if I got bad service I wouldn't return. Oh and no tip.