. >> reporter: it was in robert pike's mailbox three years ago, a legitimate-looking cashier's checkhim to become a mystery shopper. >> i was supposed to go to walmart, th courtesy of the clerks, t cleanliness of the place. >> reporter: a similar offer was just recently sent via fedex to a colleague's child, this time using a legitimate-looking money order. >> they're pretty good at n findi ways to help you artmoney. >> reporter: justin pritchard has written about scams like this and says it generally includes6 depositing the check you're sent then returning a portion of it to the scammer. >> the main red flag on all ofh t is that you're sending money. right? in almost every case you're supposed to be receiving money o but somethey convince you to send money and they're very good at that. >> reporter: via skype from colorado pritchard sat can take days before your bank figures out the documents are bogus, which is why you should slow down. >> if you let that money sit in your account and, in fact, go ahead and contact the bank, that's a great idea, just to get in touch and say, hey,