A friend of mine was one. He said he got $250 for every shoplifter he caught, resulting in arrest. He worked for Home Depot- where you find every kind of thief under the sun. He told me people would buy lawnmowers, and stuff the box it came in with tons of tools, etc.......and then return the mower for cash only. I think one year, he almost made $75k.....catching shoplifters, refund fraud artists, etc. He said the MOST IMPORTANT part about the job is that you have to look, and act the part(of a casual shopper). Also, you have to have "eyes on the side, and back of your head"......to be a productive mystery shopper, because thieves are always on the lookout for you. And, you gotta be FAST-ACTING. The average timeframe for theft, is within 5-20 minutes. That means you must tail them, from the minute they enter the store.