This article is from the Spring, but I just saw it. I have posted before about how much I hate cheap tippers and odd tipping habits. Surprisingly, Philadelphians are the best tippers in the country!
"According to Michael McCall, a business professor at Ithaca College who has studied the phenomenon of tipping, a customer's decision to tip well reflects a desire to rescue a waiter or waitress from destitution. Also, McCall says, "Tipping is partly a way to control your image."
His studies have indicated that how a person tips isn't so much about the food or the service but largely an expression of the individual. Thus, giving a sizable gratuity at a diner could be a way of saying, "I know how hard you are working."
There's no surefire way to secure a certain percentage, but McCall has noted some correlation between individuating the exchange and receiving larger gratuities. If waitstaff get down to eye level or draw smiley faces on the check, chances for return improve, he says." (source)
The Man and I give 20% regardless of the level of service and we give more when the service is good. If we don't have enough to do that --we stay at home to eat.