I remember reading in a guidebook (lonely planet?) that each of us, when traveling, is an ambassador for our country. People--rightly or wrongly--are going to judge national culture based on what they see us do. (And of course for almost any country "national culture" is a joke: there is just too much variety to generalize.)

But there is SOME sense to it: a striking example was when I lived in Thailand. Thais typically have a very strong sense of personal space, and they are careful to respect others' space. Once at a temple (Doi Suthep) my girlfriend (now wife) was bumped into by a young Thai girl. The girl apologized profusely and we thought she was going to cry, so bad was her transgression.

I'm not saying this is a good or bad thing, but that it's very very common in Thailand.

Unf, in a few decades, everything is going to converge to American culture I fear.