When prices are too good to be true

Listing sites mix pre-foreclosures with for-sale properties

A constant stream of headlines about rising foreclosures and falling home prices in many U.S. markets might lead bargain hunters to believe that there are some incredible deals to be had out there.

And indeed, there are. But are there really more than 100 homes available in tony Miami Beach, Fla., for less than $100,000?