Never ever call or email back to the type of emails you got. They are a scam. Unfortunately, Trulia seems to be full of these scammers.
Unless the owner or real estate agent can meet with you at the residence and supply ID do NOT believe they own the property.
Do your research. Go to the county website and look up the home in the public records. Find out who the owner is, whether the property is in foreclosure, or if it has already been foreclosed. I've had people email me about a property where the family had just walked away and left the door open. It was a great deal and I really need a place to live. It was a scam. I almost had half the neighborhood ready to beat me up because I tried to open the house door.
I was an idiot. I fell for it and almost ended up paying rent on a home that was foreclosed and had an eviction order on it for the previous owners. And if that wasn't enough, the jerk wrote me to say he would pray for my daughter and me because I am disabled. Bull*^$#. Those people's prayers should be saved for the ones that fell for the scam and are now on the street because of people like them.
From your question you sound like an intelligent person. Use that intelligence and do your homework on every property. Most counties won't charge you anything unless you want paper copy. Good luck.