Troubling reasons for changing credit rates.

Credit-card companies have long raised interest rates and reduced credit lines for customers who carry too much debt, miss payments, or have their credit score lowered. Now, some companies are punishing customers for more questionable reasons.

In June, the Federal Trade Commission sued CompuCredit, which issued millions of credit cards under various names, claiming that it violated the FTC Act by, in part, failing to disclose that certain purchases could reduce a consumer's credit limit. The FTC states that CompuCredit lowered limits for some customers who made payments to bars, for starters. The case is in litigation.

That's an extreme case, but other companies are looking for transactions that could indicate financial disruption, such as a layoff, divorce, or mounting medical bills. Spending patterns that seem out of habit, or the use of cash advances and convenience checks, can raise red flags.

Companies have also been changing credit-card terms based on geography and mortgage data. Someone living in a place relatively unaffected by the mortgage crisis might get different terms than someone living in an area high in foreclosures or unemployment, said Dennis Moroney, research director at Tower Group, a research advisory firm.

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