No one wants to take the blame for the housing bust in this political season, but scammers and rip-off artists in the hundreds are working overtime to siphon dollars out of the wreckage of the crash and its still-vulnerable victims.

You’ve probably heard about the loan-modification predators who promise financially ailing homeowners that they’ll prevent or forestall foreclosures. But they are really after thousands of dollars in fees, for which they do nothing.

Now the second-largest source of mortgage money in the country – Freddie Mac – is warning about a troubling new wave of post-crash fraud: scammers who illegally rent out its foreclosed and for-sale homes to unsuspecting consumers shopping for houses to lease. The bogus landlords don’t own the properties – Freddie does – and they have no right to offer them to anyone. But they use Craigslist and other online sites to advertise them to prospective tenants.

Typically the rents are tantalizing – for example $1,200 a month for a three bedroom home in a neighborhood where similar houses command double that – and the terms are straightforward: Pay us a one-month security deposit and one or two months’ rent upfront – always in cash or money order – and we give you the keys, no questions asked. The fraud promoters sometimes change the locks on the front door, remove the “lockbox” installed by the realty broker marketing the house for Freddie Mac, and they tell prospects: Oh, and don’t worry about that real estate sign in the front yard offering the house for sale. We tried to sell the house but it didn’t work out, so now we’re renting it.

According to real estate brokers working with Freddie, this type of scam can bilk unsuspecting rental home shoppers – some of whom have themselves lost their own homes to foreclosure or short sales – out of hundreds or thousands of dollars. According to Robert O’Hara, a foreclosure specialist with Re/Max Synergy in suburban Chicago, one victim told him that she lost a total of $10,000 in upfront fees and rental payments to a fraudulent landlord before being forced to leave the property.

“This is happening all over the place, in every price range,” said O’Hara. “They take the [victims’] money and disappear.” Sometimes the tenants don’t even get the keys; they fill out a fake lease application, disclose sensitive personal information such as Social Security and financial data, send the money and never hear a thing again.