Once upon a time there was credit aplenty, heaps of risky loans were arranged and, well, we all know how that turned out. Nowadays, though, U.S. lending standards are too tight. Yes, the housing market is improving. But banks are doling out loans only to borrowers with perfect credit scores. This mortgage scarcity is a drag on the housing recovery; a pity, given that both mortgages and homes look positively affordable.