YSK that if you receive an email inviting you to be a secret shopper it is likely a scam.

My wife got an email saying that they want her to be a secret shopper. They sent her a check for over $3k and asked her to deposit the money and then ‘evaluate’ a wire transfer from three different places. The check is likely to bounce and you will get stuck owing the money. I had never heard of this scam, thank god I talked to a coworker about it first. Here is a link to the FTC page on it.