I agree with our American tipping ways, and generally try to do my fair share. I'll give the minimum 15 percent for decent but not great service. My tipping policy goes up from there. Example have a 200 dollar tab, and waitress was working her ass off with our table and several others. She had one table being very difficult, but kept her head. This girl didn't miss a beat with our table we were set at all times. I got the ticket and matched the ticket price with the tip. The girl earned it. Never have I regretted doing that.

Another example, I paid a little douche a zero tip one time. His service was unacceptable we had to place drink orders twice and still never got them. But we were somehow charged for them as well as other drinks ( probably the drinks of his friends that were at another table) our food took forever, and the guy spent more time talking to bartender and his friends. Ticket comes and I get up to talk to manager about the drinks. He gladdly takes care of it no problem, gives me vouchers for another visit. I take care of the manager give him a tip personally.

We are walking to the car and someone taps me on the shoulder, and it's the waiter. He flat out asks you don't think I deserve a tip? I tell him no he doesn't, and explain why. He proceeds to turn around and call me some sort of mother fucker or two. I look and that's when I see his friends. He's showing off for his friends. Ok allow me to show off, I walk into restaurant and talk to the manager. He assures me he would take it from there. I leave and smile at the waiter as I leave. Now because it's a restaurant owned by my wife's sisters family (Inlaw thing) I learn later the kid was promptly fired. I should note that I never mentioned who I knew or anything like that. I don't feel bad about this one bit. He should have never followed me to the parking lot. Someone else could have kicked his ass or worse. The kids other mistake was not knowing that the people who owned the restaurant owned most of the restaurants in that town. So probably no waiting future for him there. So sorry for the long story, but unless the service is horrible your going to get a tip.