I would humbly say that I think your last paragraph has the usual amount of truth as any other stereotype.  Some, but not the whole story, and that is what I, and poemless are asking for, tell the whole story, or your portion of it.

Well, my last paragraph was not very diplomatic. (Consciously so.) But I did include the qualifier most americans. This was based on most of the Americans I personally have met on and off the net.

But then it is difficult to extrapolate on how people behave outside of ones own frame of reference. I haven't talked to enough Americans for my sample to be statistically valid, so I guess I might be full of shit. But it was based directly on conversations I have had with Americans.

The knee-jerk reaction by poemless to me telling about my trouble with communicating with Americans (and my theory for explaining it) fits quite neatly into the pattern. I doubt she would have reacted as she did if I said "most republicans" instead of "most americans".