You may have noticed that the mortgage industry has been troubled lately, staying out late at nightclubs, driving erratically and missing meetings with parole officers.Although there is no Betty Ford clinic for bad lending — and the end to the nation's foreclosure troubles seems nowhere in sight, you can make money from the mortgage industry's woes. Mortgage lending used to be a relatively sober and low-risk way to make decent amounts of money. You take money from depositors, pay them interest, and lend their money out to mortgage borrowers at a higher rate of interest. It's not a business model on a par with, say, search engine technology, but it used to be difficult to find mortgage lenders in bread lines. To date, making bad loans is still a poor way to make money. But investing in good mortgage loans will get you a decent yield, particularly in these days of miserable returns from bank CDs.