If they do a good job, they get a good tip.
Effort. Did they make an effort to do their job. I understand it can be busy and they might not get around to me in a timely manner, but did they make an effort. Did they see me and neglect me. Did they leave me feeling thirsty. It is a bad sign when I have to flag down another waiter because mine is nowhere to be seen. Also a bad sign if I see them flirting with a coworker instead of doing their job. I understand that they work for tips, so it really takes a lot for me to not leave a tip behind.
I always tip, even if the service wasn't great. Quality of service does play a large part in how much I will tip, but I don't have any rules. I just tip what I feel is appropriate -- I do try to keep it at or above 15% though. I feel like if you can't afford to tip, you can't afford to eat out. It's just not a valid excuse.
The quality of their service. Regardless of how bad the food was.
I think I am pretty awesome. Thanks!!
How good of service I got while I was there