I worked in the dive industry as an instructor for a few years and spent a lot of time on dive boats. In that time I came across a lot of tourists. On the whole I have to agree that Americans are usually very polite when overseas and any complaints from them are generally justified. You get a few bad ones of course (loud, crass, arrogant, and full of "oh but it's not as good/big/expensive as the one we have at home!") but you get that with any group.
