When i first arrived in China i had a contract with an agency there to go and teach English.
Before i booked my flight ticket i checked everything with them: i checked where exactly i will stay, what level i will be teaching, i checked how many hours i will work and how much the salary would be (which is always a tempting salary) and I made sure i had a contract that is fair enough for me and for them.
As it turns out later most of these agencies don't really care about the contract because they know that once you are in China you are just an individual against an evil mafia (yes i like to call them mafias) because most of them have connections with people in the government ("Guanxi" which means relations in Chinese) as well as some police officers and lawyers on payroll.
So once you arrive in China everything becomes so different with horrible treatment and broken promises you find out that you paid an expensive flight just to arrive and live in a small room that stinks and you teach more hours than you were promised and not getting your full salary because they always find a reason to deduct some money.....that's of course in case they were kind enough to give you work in the first place.
And then you realize that there's nothing to do and that in the end they win because you wasted so much time and money trusting their promises and working for them while they make the big bucks and you are just stuck with them because you can't change your Visa without a release letter from them.
My advice to you here if you get a job offer in China teaching ESL (English as a second language) or Maths or whatever you were promised is that you should forget about the contract itself and forget about the promises they make....you just need to focus on finding reviews and maybe contacts from the teachers that worked for them previously.....you can even ask the agency for contacts of teachers and do your best to find information about the agency and how they treat their teachers and whether they will let you go if anything goes wrong.
I always say that an agency that easily provides their teachers with the release letter are a good one because they don't try to force you to stay with them in very bad conditions.
Later on i'm planning to post the details of what i experienced in China and how i found a way out of this and i will also provide some useful links to guides you should read and articles from teachers in china who had bad experiences so you know what you are getting yourself into.
Feel free to contact me with any information you need regarding this topic.
Did you have a bad experience with a certain teaching agency in China? if yes please let me know in the comments to raise awareness.