@IrishHeather, that has become very common here in the Houston area, as well. I actually found some ads like that when I was looking for this place. What they do is see a desirable ad, and copy it exactly, then re-post it with their contact information, but lower the price significantly, which draws people in. So, what we can learn from that is if the price is too good, it's probably not a legitimate ad. I saw several of them back then, and I backtracked the listings, contacted the actual realtors, the police, and the local news stations, to advise them. In some cases, they will go to the house, usually one with a lock box, and change out the lock for their own, so they can show potential renters (aka pawns) around, as that man did with your sister. It's a profitable game, wherein they can collect first and last month's rent, pet and other deposits, and make off with it all, before anyone even realizes they've been duped. It's happened here where people have actually moved in, turned on utilities, etc., and are then out all that money, which is usually all they have to their names. It's a very sad situation, which is why I went to the trouble I did back then. I hate seeing people scammed, and even worse, harmed or killed.
I've bought items through Craigslist ads, but it's been a long time. It's scary nowadays, like the wild west, but as some others have found out lately, not everyone will be a victim, and I think we'll soon be hearing stories of potential victims of these transactions fighting back. It seems that is what it will take to deter criminals, because they're obviously not afraid of being caught by the police.