Interest-only loans--a villain in the subprime mortgage crisis--have made a comeback. But now the bar is high for would-be borrowers.Today's interest-only loans--in which a borrower makes monthly interest payments but puts nothing toward principal for a set time period--are almost exclusively a jumbo-level product for wealthy borrowers. Jumbo mortgages are loans that exceed limits of government-backed loans, $417,000 in most areas and $625,500 in some high-priced areas.Lenders have tightened qualification standards and mostly offer interest-only options for adjustable-rate mortgages (ARMs) rather than 30-year, fixed-rate mortgages. Most lenders think interest-only mortgages are very safe because the borrowers have strong credit profiles and generally put down large down payments.For example, a borrower usually needs a credit score of.......click to read.