You get the credit card offers in the mail all the time. “Earn 100,000 miles if you spend $3,000 in the first three months.” Sounds easy enough. If you worked at it, you could spend three grand and then take a couple flights for vacation.

But if you’ve ever been tempted to sign up with the intention of spending the minimum, getting your miles, and then cancelling the card, you might want to reconsider. More and more airlines and credit card companies are cracking down on consumers who attempt to work the system, cancel the cards, and sign up again 18 to 24 months later.

The practice is called churning, and it can actually work against you.

Last year, USA Today travel columnist George Hobica warned of the dangers of churning credit cards as a way to game the airline’s system.

A messy stack of credit cards - Churning credit cards can damage your creditFor one thing, your credit score will take a hit. It may not seem like a big deal, but be aware that repeatedly applying for credit cards makes you appear to be a higher risk than those who apply less often. And if your score takes a hit of a few points and you own a home, your mortgage lender or credit card lender might increase your rate. Then those “free” flights aren’t so “free.”

And let’s be frank: do you really spend $3,000 in necessary purchases in a three month period? While credit card companies dangle the carrot of frequent flyer miles, they’re hoping you’ll be unable to pay off the balance and be hit with their exorbitant interest rates. They’re also hoping you don’t read the fine print to realize that there’s a relatively steep annual fee you’ll be paying, should you decide to keep this card in your portfolio of plastic.

Some of these dual credit card issuers are also putting a limit on the offer, like one time per customer. The American Express Delta Skymiles Card awards bonus miles once and once only. The Capital One Venture Card allows you to use the miles you earn on any airline, but you can only open an account and get 40,000 miles once.

If you still want to play the game, here’s one last warning: if you open too many credit cards, the next time you really find one you think has a great deal, you might end up being rejected. George Hobica said that, despite an excellent FICO score, he was turned down for a particularly great deal because he had opened too many credit cards in the last two years.

Do you take advantage of the credit card offers? Have you tried churning credit cards to boost your mileage or points? Do you have any suggestions for your fellow travelers on best practices? Share your ideas in the comments below, on our Facebook page, or in our Twitter stream.

Photo credit: Nick Youngson (BlueDiamondGallery.com, CC BY-SA 3.0)