If I were to stay at someone's houe in the United States, I would probably already know what would be, or not be acceptable behavior. Through observance, and clarifying questions, I would figure out the rest because as a guest, I would never want to make my host uncomfortable.
The same applies to travel in foreign countries. A little research helps avoid many misunderstandings for acceptable dress, picture taking, alcohol consumption, social touching, etc. The idea is to blend in, interact as a local, and enjoy the culture.
As far as foreigners trying to adjust to the US culture - I've found that they usually DO try very hard to understand the culture, speak a few words of the language (even bring an interpreter) etc. I have found foreign visitors to our country to be enegetic, good humored, usually well educated, humorous and frankly charming.
Or perhaps I am just extremely fortunate to meet such consistantly likeable people!.
angela