Foreigners don't discriminate against Chinese people casually, and I believe that people with poor quality are looked down upon by anyone. The only reason for this is that there are more poorly educated people in China, so there are more people who are looked down upon, which then creates the misconception that foreigners are looking down upon Chinese people. In fact, there is no such thing.
Australia has more than 100 nationalities and is a very diverse society, so don't be so ignorant as to say that.
Of course there is racism everywhere, and those troubled youths are an isolated problem, not a general phenomenon. We Chinese look down on the Vietnamese and North Koreans as well.