Oh, wow...couldn't possibly agree strongly enough with Turnoi and Silver.
Recruiters, in a word, are scum...or at least 99% of them seem to be. You don't want to take the chance that you're going to come across the, oh, 3 or 4 good ones in all of China that may not even actually exist. If you read back into the deep archives of EFL internet-dom, you'll read a very disturbing number of horror stories stemming from the use of recruiters.

Recruiters have been known to lie like a rug...promising you a Hainan beach school and delivering you unto the frozen steppe of Inner Mongolia. Recruiters have been known to promise things the schools won't actually deliver. Recruiters have been known to hold passports of working teachers...and if there's one thing you should know it's to NEVER teach while your passport is being held hostage. Other than the very necessary process of getting your Residence and Work Permits, there's no reason on earth for anyone to hold your passport- except to be a threat to you. Recruiters have been known to place teachers, and then simply disappear, leaving teachers in the lurch (or worse) if there's a dispute or other problem. And much more...

And...recruiters tend to pimp crappy gigs...low-paying, oppressive jobs in toilet-hole cities that can't get teachers to come on their own.

It's, like, SOOOO easy to find jobs without using a recruiter. The schools are dodgy enough already...why add another layer of unnecessary parasitic sleaze?

Don't reply to recruiter ads. Ever. If one contacts you, delete the message without responding. Always deal ONLY directly with the hiring schools!