I have been doing this job for around 8 years, and I find out that there are very big percent of foreign teachers in China just garbage.

Oh yes, there is garbage everywhere - in the streets of big Western cities and in backward places in China with lots of rats around attracted by the smell of garbage. And some Chinese people in that area even do not care to put their garbage into bins where they belong, and they do not care about the rats around either.

Applying the term "garbage" to humans is quite another thing. If a larger part of foreign teachers in China are just garbage as you suggest, then my reply to you is this:

Yes, that's really true in some cases. But the number of garbage Chinese "schools" with lousy bosses, mean and greedy, cheating and deceiving as they are, incompetent school management, native Chinese "teachers" who can't speak a word of English themselves, garbage housing given to foreign teachers- all this is much more frequent than the number of foreign garbage teachers you are talking about.

And you know what - garbage attracts other garbage, that is in plain language: A garbage "school" probably attracts "garbage" teachers. If that is correct, then you might know why you have come across so many "garbage" teachers at your place.

I know a very simple solution: Do NOT employ foreign "garbage" teachers, and all your problems regarding foreign human garbage would be solved.

But maybe, no other (decent, non-garbage) foreign teacher wants to work for an obvious garbage place like yours. If so, all of us have what we want...hahaha!