You can't trust an awful lot of people in China, whether Chinese or foreign. Friendships are often only transactional or temporary, people may cheat you, people may finish assignments and move on elsewhere. It is sad but true, but when you get more used to the culture, you don't tend to think too much of it.

I also don't like to whore my identity out on the internet too much, people who are relatively new to the internet and don't understand its traditionally sick and twisted sense of humour, get a bit too sensitive these days and will hold anything posted in your name against you. It is good to post on forums that aren't too politically correct and just let the crybabies leave of their own free will after the rest of the board has humiliated them.