Chinese sports fans have been far more rude in the past, for example to visiting Japanese soccer teams.
In terms of rudeness they are no where near some of the NBA fans, especially for fans from Utah (personal opinion), but this is Olympics, athletes don't get hundreds of millions to compete, I wish they would receive the proper respect and I think they probably will. After all, the Chinese attitudes toward the Japanese and the rest of the world is fundamentally different(not trying to start a flamming war, but just stating basic fact).
Booing athlete based on Political division is against the spirit of Olympics, an attitude which CCTV has been painstakingly cultivate amongst the general population. WE ARE throwing a party in our OWN HOME, it is best for all Chinese to bring out their best behavior. I think if people can improve their politeness and other thing, then all the trouble of hosting this event is worth it and so much more. I mean just compare the cleanness and politeness of Singapore and some Japanese cities to Beijing, not saying Chinese are the only ones have problems, but as long as there is room to improve, then we should.