Some travelers end up working in Thailand and some come to both travel and work.
These people or teachers are prey for the so called education scams or fake job agencies. Think of business practices, from extortion, to theft of personal property, miss leading advertisement, not paying salaries, threats against schools, teachers and other staff members. One of them even has Thailand's Natural Resource and Environment Minister Suwit Khunkitti involved!
Unique Suggestions: First warning is when you are not paid in full or when your money is "late", or when you have to do more work or overtime that has not being paid. Tempting to believe lies as "i'll pay you in a few days" or "you'll get a raise" only to find out that the longer you stay the worse it gets! False promises has been made about workpermit and visa paperwork? That happens all to often.
Fun Alternatives: Just stay away from 'agencies' altogether is the best! Some schools only work with agencies and share the profit and corruption. That means when you not get paid by the agent the school still pays the agent and for doing so the school get some of that money back from the agent and it'll disappear into the pockets of usually the owner or director of the school! This is how some agents and school directors in Thailand make their money. Do some online research first before you start working somewhere. Best thing is a school who doesn't work with agencies although some schools are just as bad i have to say. Beware of schools like Streesmutprakan school , Nongchok and Sarawittaya School.
Beware of agencies like Kirk Pathumanun's axiom, edknovate, smartkurve, exact academy and Quest language school and a person named Arthur Wood.