It's never been problem here as we are ‘judged’ on our work and how we relate to students and colleagues.

In many schools around China teachers are judged on appearance as much as on teaching quality. I'd tend to agree that it doesn't mean that you have to dress formally but school administrators and students alike often have an idea in their mind of what a foreign teacher should look like and certainly early on you'll be evaluated on how closey you meet this stereotype. The very definition of judging a book by it's cover.