I am glad you got your visa back, but the way you went about it was wrong. I can't imagine someone letting themselves be bullied so much.

It all depends on the individual foreign teacher as well as the unique situation there. One cannot make hard and fast rules. If said teacher can continue working there until his (or her) contract is up, and if deciding to leave or being discarded by the employer, at that point in time, gets a satisfactory release letter allowing him (or her) to move on unhindered, mission accomplished, I say. Treating the school waiban and his immediate family to a good dinner once a month can have astounding results - I observed an FT who tried his best to teach, but couldn't, continue his employment in China through this cunning approach while one of his fellow FT's, a meanie and deemed a troublemaker by said waiban for being 'too forceful', sic, though an excellent teacher, got a bad release letter.
The end result is what counts. Achieve it immorally, if you like, but succeed, whatever strategy you employ! Remember that Chinese culture is diametrically opposite western culture in some ways. Things work here that couldn't work in the west. Use them when and if necessary. Of that, be aware!