What usually happens is the scammer will pose as a buyer to elicit as much information as they can from the real seller. I had the same thing happen to me about 5 years ago, and I sent a whole stack of info to the person inquiring, who then used that info to bait other people!
Ironically enough, the scammer advertised my car on carsales with a fake phone number, but I had my real number stuck on the car itself (in the pics in the ad), so a buyer rang me on my real number from the fake ad and ended up buying it!
419eater is an awesome site, highly recommended.