Sigh.
Seems you try to misunderstand everything I say. One last try on my side. Backwards.
Lance Armstrong issue. The behaviour near the road to Alpe d'Huez was bad - against different cyclists from different countries (e.g. one German they thought made something wrong the day before, he just did his job though). And there were several Americans which were NOT treated that bad. Fans were very unfair - they were drunk. Drunken biased fans from anywhere in the world have rude behaviour. It's bad - but it's nothing which is especially directed against Americans.
Worlds 2004. I am reading several skating boards, and have NOT read such announcements - but things like that would be ruled out by good administrators anyway. As several reported - they were no boos in Dortmund against Kwan, neither against any other American like Weiss e.g. afaik. And could you please accept that (perhaps with the exception of Russia and Ukraine) no European television talks about Cohen's ancestors? For our tv people she is American. Full stop. The only difference our broadcasts make between her and Kwan is the length of their career (and of course things like skating style, coaches and so on). For them Cohen is rather the young blood, but even more so of course Arakawa and Ando. Many were sorry for Kwan btw, not cause of her deduction (most wondered why she would risk that), but because of her bad qualification round - otoh it makes the competition more interesting to see three ladies having good chances instead one big favorite.
Athens 2004, thursday 26th. It was an awful behaviour of the audience - but again your conception of the incident seems so narrowed..... Most of the loud Greek in the audience did not cry something like "bad americans" or whatever - they had posters with the name of Kostas Kenteris, the greek sprinter who is under the accusation of doping. They bought their tickets beforehand for this evening cause they wanted to see him win. Now he was out and they were disappointed. It makes me angry - cause I think it's stupidity (to use a weak word) to cry for a doper!!!! Besides his name they were mostly crying "Hellas" (greek name of Greece itself). Nationalistic. Unnecessary. That was the biggest part of the uproar.
The smaller part of it is the doping problem itself. The drugs came from the US. And there are suspicious wins by US sprinters (quoting doping investigators here), this might make the people in the audience even more mad. Their "doper" is out and others who might as well dope are in. Yes - in this respect it was against the US sprinters. Cause there are big doping affairs in the US atm. Or shall I say - they come out now. And not all is out already.
If the US team (talking of sprinters here mainly) acts like it does, which means trying to hide everything, not helping to clear it up, the reputation of those sprinters might well be going down more soon..... But this is not about the nation as a whole they come from - it's about systematic doping. It's the same problem Bulgarians in weightlifting or Hungarians in discus have. And I know quite well there might be many more than we know now.
You could see the difference last night when the audience was cheering for two pole vaulters (where doping does not help and no accusations of doping are at hand against any of the athletes in the competition) - which came by chance from the USA. They were good in the competition, the audience cheered - everything ok. I don't know about the situation in boxing cause we don't get much coverage of it. But judging from the very different events we got it seems the audience does NOT generally boo against US athletes. The only real accusation I could make is that the always cheer a lot more for the Greek athletes (if present) and not that much for any other from other nations, which is already bias. But again - that's the case for many competitions all over the world. And I can certainly say that US athletes are NOT booed in most events in Athens. If you get that impression maybe I should not only blame you but also your tv coverage...... This could well be an example about the influence of mass media.