Payday and car-title lenders tend to cluster in low-income neighborhoods—especially around military bases, where families are young and borrowers aren’t very savvy about interest rates. Congress recently slapped a 36 percent interest-rate cap on loans made to members of the armed services. But it left out everyone else, who pay rates that sometimes exceed 700 percent, says CFA’s Fox.

Of all the predatory loans, “exploding mortgages,” with interest rates that wing up after two or three years, are probably the most toxic and have made the most headlines. They’re typically granted to borrowers classed as “subprime”— those with credit scores under 620 (a 900 score is tops). But these are the very people least able to handle monthly payments that suddenly double or triple.