Actually, one thing I HAVE noticed is that Canadians in Boston, and there are a shit ton of them, don't have any sort of rep for being bad tippers. In florida though, they are pretty much the worst. Europeans are always the worst, they leave like 50 cents and say what a fantastic job the server did on the way out. Or even worse, they will KNOW they should tip, and explain to servers why they don't tip. Canadians just don't tip, and if they do it's like 5-10%.
Surprisingly the British aren't really known as bad tippers. It's the continentals and Canadians that get an awful rep. South Americans tip like 40% and then ask to f**k the waitress or start getting their own wine and shit haha.