I tip generously as a rule. Generally that means 20%, maybe just under 20%. Bad service, I do the "minimum" 15%. I have never not left a tip at a restaurant.
That said, I also have started avoiding giving my business to places where tipping is the norm, precisely because of the general attitudes surrounding tipping in America, as heavily exemplified in this thread. A tip isn't really a tip if it is expected, and so yes, I do cook my own food (see the cooking subforums
) and I eat out infrequently, and I get in my car and pick up my own pizzas.
I'm not fond of the idea that if I don't make a "voluntary" donation in the form of a tip I am a bad person or will be scorned by the person expecting the tip. And so, they don't get my business. Granted, since I don't skimp on tips I am unlikely to invite the scorn of the tippee, but the false sense of it being voluntary is something I do not like and generally don't support with my dinero.
And yes, I have worked as a waiter and made the two something an hour myself. At the same place I worked as a dishwasher, and in both cases, I made minimum wage (or more as was often the case as a waiter).