This crimes have victims in multiple streams. First of all, the renters who sign these "fake" lease agreements doctored up by criminals are soon evicted after signing their names, moving in, and going out of pocket thousands of dollars. Then the banks or other owners of the vacant homes are extremely inconvenienced and forced to lose money re-marketing the homes after evicting the victim tenants. Real estate agents are subsequently inconvenienced and the integrity of sites such as Craigslist are put into question through no real fault of their own.
The criminal predators will typically seek out a home rental listing on a place such as Craigslist, copy it, reformat it with their phony numbers and phony contact names, and then market the property until the unknowing victim takes the bait. After breaking into the homes (and sometimes even re-keying the houses), they collect upfront rents and deposits (likely in money order, money transfer, or cash as to be untraced). Tenants then lose thousands of dollars with little recourse until perhaps the perpetrator gets arrested and prosecuted--this rarely happens. If and when the criminals get caught they face off the bat tens of thousands of dollars in bail bond amounts along with local and federal felony charges.
Please be careful conducting your rental and even home-buying search. I recommend you contact a legitimate REALTOR for these transactions. Protect yourself please. As the buyer or tenant, you rarely go out of pocket for anything as the Seller and Landlord typically compensate the real estate agents.