Depends. I've been to counties where it's rude to tip.
And in Europe they generally have a service charge that is already added to your bill.
not if the waitress goes out for her smoke break and takes 15 minutes, then proceeds to breathe her cigarette breath on my children.
Ohh man I know it drives me nuts when my coworkers go out to smoke and come back stinking..yuck
I tip based on service. If the service sucks, my tip is going to suck!