Rental scams are common here and on any site that allows the general public to post. Please be very cautious with deals that seem too good to be true. NEVER send money expecting keys back by mail.
Read the scam warning Trulia posts. I've attached a link to it below.
When you find a questionable listing please go to the More button on the listing and then hit the FLAG button on the listing page to warn Trulia and others.