Unfortunately, it is very difficult for sites like Trulia, Craigslist, etc. to police these kinds of scams. On a national basis, it would take an outrageous amount of work. Or the sites would have to charge for listings, which would mean they would have very few listings, which does not help renters like you either.
But scam artist know this and they do take advantage. Often they grab photos from "for sale" listings and recycle them as rentals, frequently at price that are too good to believe.
The main thing to always remember is to protect your own safety and finances. Your radar should always be up in these situations. If your instincts tell you something is wrong, run the other way. Don't send money via mail. Don't wire or Moneygram money. Don't give out financial information of any kind. Don't ever go alone to look at rentals. Watch out for anything suspicious (like a "for sale" sign in the yard or an "owner" who claims to be out of town and suggests you just go look through the windows).
And it does not hurt to ask a lot of questions and do some checking. Often you can confirm owners' names in county records online. Usually you can find phone numbers for neighbors online. You can call and see what they know. And, whether you are in contact with the "owner" via phone, e-mail or text, you can ask for a lot of neighborhood information. Where is the closest grocery. How far to the library. What is the elementary school. Real owners know these things.
The internet is a great invention. But it does let the crooks, scam artists and others hide and we all have to be more careful when dealing with people electronically.
Prudential Real Estate of the Rockies
(Soon to be Berkshire Hathaway HomeServices)