The basic idea is to bet somebody else's money. Pick a hot market where prices are going up and chase them. Get as close to nothing invested as possible through high LTV mortgages, stoked by mortgage insurance if necessary. Sell in a year if the price went up. Rents are just partially covering debt service.
If the price doesn't go up you have a huge mortgage liability to service and nothing much to show for it. Default. Give the house to the bank. Let it be the one to sell it at a loss. Not very honest, and won't do wonders for your credit rating. I don't doubt that a few operators get several "hits" in a row and make money, though.
(PS so do people who play craps...)