Generally speaking, shills have substance abuse problems, often various deviant behaviors, including but not limited to fetishes, compulsive lying, or kleptomania. Basically a lack of control which eventually led them to get into this kind of situation. I would imagine that the pay scale for those who are paid is equivalent to that of an entry level support position, and furthermore they are likely to be outsourced to other countries where English is at least common enough to keep up with the attrition.