I think there's some middle ground. Yes, one should do what is appropriate in the country where you're visiting...but that doesn't mean you leave your own culture's sense of fairness and decency at home when you travel. Tipping $2 or $4 on a $200+ room can hardly be described as inappropriate.

I think I know what you're getting at, but let's clarify. Are you implying that my "overtipping" the natives makes life difficult for those who follow because I've contributed to the expectation of higher tips? While this topic is larger than can be -- or should be -- dealt with here, let's just say that I take a very dim view of this argument. Who is the arbiter of how much I, as an American visiting Vietnam, "should" or "shoudldn't" tip? (Or whether I should tip at all.) I've been travelling for 20+ years myself, and in al honestly, I don't think being a generous tipper has caused egregious social harms.