As shoppers hunt for deals this holiday season, it's crucial to be aware of scammers.

John Henry, of Hartsdale, received a FedEx package with a check for nearly $3,000 to be a mystery shopper. Luckily, he picked up on one of the most common red flags with scams— poor grammar.

"It's the holidays, there's a lot of scammers trying to take advantage of seniors and anyone they can," Henry says.

He was targeted in a common check scam. These usually start with a check in the mail sent to a secret shopper. The recipient is instructed to keep some money and send the rest to "test in-store" money wires, and buy gift cards that you send back images of— both common red flags for scams, as both are like sending cash.

As for the check, banks will make money available in days but take weeks to realize it's fake. Once that happens, it'll bounce and leave the person who was targeted on the hook for the money.

Better Business Bureau President Claire Rosenzweig says, "Watch out for unsolicited offers. Check to be sure it is a legitimate offer. Whenever it involves a check being sent to you, it's a warning sign." The Federal Trade Commission put out a warning this week for another check scam that targets college students with part-time work.

A search on the BBB's online scam tracker shows how popular these types of scams are.