They usually can't. And if they could (speaking as a banker here) they would lose their shirts. We're not really IN the real estate business. It's why foreclosed houses usually get sold at auction and not by Realtors.
In Washington state, there was (may still be actually) an attempt by banks to sell real estate. BTW, the house I rented was going into forclosure and another guy (an investor) came along and bought it pretty cheap. There were two mortgages and one of the companies almost killed the deal.