You get a check for more than $2000 and a letter -- which comes with instructions. The instructions tell the receiver to cash the check, buy some cards at a local store, and send in the numbers -- but to an email.

The check is a fake and bounces a few days later. You just spent your own money and sent most of it to someone you don't know.

Lampasas resident Steve Miller caught the scam quickly.

"The main thing was the routing number... all routing numbers as far as I know nationwide have nine numbers," Miller said. "This one didn't."

But at first glace, the documents looked legitimate. Someone paid $23.75 to send it though priority mail. The check has a logo of a real bank. The letter has the logo of Mystery Shoppers Inc., which is a real company.

Miller is concerned older people in the community might not realize the check was fake.

"A lot of the older people don't have people to fall back on, their friends have passed, a lot of them are lonely and they like to talk to somebody," Miller said.

However, there are legitimate mystery shopper organizations, and there are some easy ways to spot the scammers.

Rule number one: if you didn't sign up before hand, it's probably not legitimate.

"If I didn't apply for a job with Mystery Shoppers, then how is this legitimate?," Better Business Bureau Regional Director Adam Price said. "That's the number one red flag right there. How do they even know who I am?"

Even if the company claimed you signed up, there are things real mystery shoppers or secret shoppers won't do.

Rule number two: Real companies wouldn't pay you upfront.

A business alert on the BBB profile page for Mystery Shoppers, Inc. states:

"Mystery Shoppers Inc. does NOT pay shoppers up front for the shops that they are doing. They do NOT send you a check and ask you to cash it..."

Rule number three: A legitimate secret shopper company will never ask users to buy pre-paid cards.

"Any time a company asks you to purchase a green dot debit card or money pack card walk away, or run away," Price said. "Once I read that number off to a person on the phone, the money is gone and I get nothing."