I'm sketchy about tipping, mainly as I'm always anxious about where the tip money actually goes to. I know that it used to be not so long ago in the UK that tip money could be taken by the company to cover staff wages, which I thought was terrible, so I always used to ask where my tip would go to. Thankfully, the law has changed, but even so, I'm anxious about tipping.
For me, there are 3 things that make a good meal: service, food quality and atmosphere. When you tip, you usually take all of these into consideration to come up with a suitable amount you wish to tip. However, it's very, very rare that any of the money I tip goes to people who I feel deserve just as much credit as those who serve me - the chefs. I really feel for them as they can do an excellent job preparing the food you actually eat and them get **** over because as a society we kind of ignore their part in the creation of the meal when we hand over our money to the waiter/waitress.
So I sometimes tip, sometimes don't. In all honesty, I do tend to tip the more attractive waitresses even if they do a piss-poor job.
I'm going to hate doing to the States and being FORCED to tip way over the top...