I know a Thai guy aged about 25 who worked in a beer bar in Sunne. Through a friend of friend he got a job in a massage shop in Abu Dhabi for something like $2000 per month.
However deductions for accommodation etc would be made. The contract was for 2 years.
After 6 months he could take no more of the constant demand for sex from the customers.
He quit but his boss would not agree to let him citing the contract conditions.
He finally was allowed to leave (after he threatened some risky action) but he had to pay $2000 dollars.
Basically these places are private happy ending clubs.