Mystery shopping is real but if you got a check before doing the work it is a scam. That check will bounce and cost you fees, plus the scammers usually tell you to take your fees and expenses out of the check and wire transfer the balance on to someone else. They hope that since your bank will allow you to access the funds before they have really cleared through the other bank you will rush to get the job done before you discover that the check was deemed fraudulent. Participating by having deposited the check and withdrawing the funds can have you presumed guilty of participating in fraud as well.