Just like when using Usenet, you're expected to hang around and check out the local culture, read the stickies (group FAQs on Usenet), and so on, before posting in web forums. The information on what is acceptable and what is not is available. Maybe the very first time someone uses forums it is reasonable that they might not know this, but if they've been on the Internet for more than a week they really ought to learn good manners.
It's not something which being from another country should impact. I first got on to the Internet when I was living in Finland for several years during the early 1990's, and the rules were no different. I would suggest that most of the people on this forum are not from the U.S. either.
Torben
Torben