Being a secret shopper can be a great opportunity to make money but it can also cost you your hard earned cash.  Scam artists are luring people in with offers to rate their experience at big retailers.

Nancy Salsgiver almost became a victim when she received a check in the mail.  "I thought, hmm, that's strange.  There's a stamp and it's from Canada," she said.

Salsgiver received an envelope in the mail that contained a $2,800 check and detailed instructions for a secret shopper assignment.  The letter claimed the check would cover the cost of shopping and her salary.  Salsgiver was asked to rate well-known stores like Walgreens, TJ Maxx, Best Buy and others.  Her assignment was to rate on appearance, service and attitude on a scale from 1-5.  Then, she was asked to fax the survey to a company called I.F.A Systems Info Source in Buffalo, New York.

"The instructions are to deposit this check in your bank," she said.

But that can really end up costing you if you're not careful, says Vince Gottuso from the Better Business Bureau.  "You're out of the entire amount of money.  And whoever you wired through Western Union or Moneygram has your money and you have no way to find them," he said.

The FBI says the scam goes like this:

1. You unknowingly deposit a bad check.

2. The bank takes 5-10 days to figure out if it's bad.

3. You withdraw the money for the shopping assignment and wire money back.

4. You don't know you're out the money until the check bounces.

5. You're stuck with the shopping bills and you've overdrawn your bank account.

By this time, the money you wired is in the hands of the scam artists.

The experts say if you're given a check and asked to return a portion of it back to the person that's giving it, that's a big red flag.