Tipping in the US is a bit of a scam. An ever increasing percentage, it seems.

As I have travelled more, it's become more obvious. I was in Australia last month, and had generally good service. If I felt like tipping, I did. If not, I didn't.

I'm in Thailand now. Most restaurants add a 10% service charge. That's fine, as well.

I generally start at 10% in the US, and top out at 25%. Lackluster service gets the 10%. I even had a waiter change a 15% tip on a credit card slip, to a 45% tip, after I left. (Meal $10. Tip $1.50. Changed the 1 into a 4)

There seem to be a lot of restaurant servers on this thread. Saying you deserve to get your food spat on because they don't like the tip, is just criminal. I've known servers/cooks who have gotten arrested for it.