This is a topic you see every week on TV Court shows where someone gets a big check, tricks a friend into cashing it, and then it bounces a week later.
What keeps people hooked is, SURPRISE, the there really are secret shoppers!
I investigated this several years ago by applying and becoming a secret shopper entirely over the internet. It was a 100% legitimate operation.
What made that secret shopper "job" different was the way it operated.