Doug Watts says buying his televisions with a deferred-interest credit card from Best Buy was one of the dumbest moves he ever made. A nasty surprise came in the mail, when the three-year promotional period was up. Doug Watts "They added 1,300 dollars in interest on a balance of roughly 7 or 800 dollars." The original receipt Watts signed contained loan terms he says were hard to find and unclear. But they said if he didn't pay everything off in three years, he'd be charged interest on the entire bill - even on the money he'd already paid. Attorney and financial expert Christina Tetreault says although the terms of deferred-interest cards have recently gotten clearer, you can still get trapped. "The disclosures on these cards are really not enough to help consumers understand what they're actually buying." Besides Best Buy - Home Depot, Walmart, and other retailers promote deferred-interest loans. You'll also find solicitations for deferred-interest credit cards designed for health care expenses in doctors' offices, a setting where people struggling to pay for care could be most vulnerable. Christina Tetreault "The very location of the solicitation within a doctor's or a veterinarian's office or a dentist's office is inherently exploitative." Consumers Union, the advocacy arm of Consumer Reports, says deferred-interest cards, while legal, are dangerous financial products and often carry high interest rates. Christina Tetreault "They should be banned." As for Doug Watts? He says he'll never fall for another deferred-interest credit pitch again. ."