How can companies make more than a billion dollars selling a service that almost no one wants? By signing up millions of members who don’t know that they’re becoming members.

A survey by credit card company Visa estimates that nearly three in ten Americans have been stung by a subscription trap. Here’s how it works: You buy airline tickets or flowers or a digital camera at a site like Orbitz, US Airways, or FTD–and just when you think you’ve completed your transaction, you get an offer for cash back or free shipping. So you click the button, and a screen appears asking for your e-mail address in exchange for that attractive little benefit. It seems like a small price to pay, so you comply and then finish your purchase.

188640-sneaky_180Three months later, as you review your credit card statement, you discover that you’ve been dunned for $50 in membership dues by some company you’ve never heard of, for a club that you never knew you belonged to and that you’ve never received any benefit from. (Even when the offer promises something like cash back or free shipping, those promises often apply to your next purchase, not the one you just completed).

Unfortunately, getting your money back isn’t easy. According to some angry consumers, getting a full refund required writing a letter (the old fashion way) and waiting months to receive a credit card chargeback.

Welcome to the world of posttransaction marketing, a billion-dollar industry that most people have never heard of.

Click here to read the complete article on PCWorld.com.