To them, it is more important that you are doing well what they expect you to do and do not make any problems to them. If your students are happy, they will tell the school, and then you are a "good" teacher.

That's exactly right, Turnoi. The main thing is to keep your students happy. Then everything will be hunky dory. Permit me to add that its also a good idea to keep the dean of your department and the uni foreign affairs office happy too. Personal relationships in China are oftentimes more important then actually whats taught.