Like any part of the world, agencies will yes you to death and tell you what you want to hear to influence and induce your decision to sign on the bottom line. Beware of these types

However on a positive note, there are a number of agencies tied to China that are very reputable. They will work with the CAAC and Chinese Department of Immigration in helping ex-pats be properly certified to fly in China. Again due dilligence is important on your behalf before signing a contract for employment.

Request, via PRUNE or even AIRLINE PILOT CENTRAL, for information on employment agencies that have contacted you. I'm sure you will recieve replies.

Good luck.