The other side of the issue.
Yes,there are a lot of bad "schools" and agents in China but there are a lot of bad teachers too. China is becoming like the old Wild West, a place to get away from debt collectors, child support payments and the like. I recently interviewed over 60 applicants for teaching jobs via Skype, only 5 could write properly with many initial email applications written in text speak, RU instead of are you etc. When asked what book they would suggest for a class most were unable to offer a suggestion admitting that they seldom read books. On being asked to submit a sample lesson plan, again most could not be bothered. These same teachers demanded up to 30,000 a month, quoting supply and demand, due to the recent expulsion by the Chinese government of many "cowboys" calling themselves teachers. Only one applicant has been employed.
Teaching English in China is not all about singing and dancing like a performing monkey in kindergartens as many people seem to think.Nor is it about chatting up the "hot chicks" in high school classes. Likewise, those who come to convert the locals to their particular religion or alternative lifestyle will not endear themselves to anyone.
On the subject of sick leave, if you need to miss one class in every three due to a hangover or because Tuesday is the only day your chosen hairdresser is available don't expect to be paid. Your social life should be arranged around your job not vice versa.
As for contracts, what many don't seem to realize is that most contracts include a probation period. The employer OR THE TEACHER can void or renegotiate the contract during this time. Anyone with their wits about them can see in a few days if they have been mislead by the school or agent the same way we can see if you have mislead us regarding your abilities and attitude.