Very often. Or will not get hired.

Controversial maybe, but I often wondered if the Chinese experience of black people has been bad because the Guangzhou blacks are not representative. I've often found their behavior to be questionable.

It's definitely true, I regularly get schools asking me not to send them black teachers, I disagree with such practices of course and went as far as cutting ties with some of them.

Although in my experience, it happens less and less often, also because the supply of Foreigners willing to teach in China is dropping big time this past couple of years so they don't have much of a choice but to become less 'picky'.