I played along with one of these a while back... can't remember what I was looking at, think it was a newer 5th wheel camper. Anyhow I was really bored so I played along. We exchanged a few emails and I made it a point to say how it is exactly the model I was looking for and this and that. I played along trying to be very gullible, but when it came time to get to the nitty gritty they said that the camper was in a shipping terminal in Florida or something like that, and not up here in Ohio where the listing was for. I said that was fine, I had family there and would be traveling down there in a couple days. He insisted that it had to be shipped and I would be able to return it within 5 days or whatever but I said that I had to go away on business trip so I had to see it first since I wouldn't be around long enough later to check it out and return it if there was any problem. I told him I'd even offer him an extra $3,000 if he would let me drive down and see it in the next 2 days. After that he never emailed me back.

It is never mandatory that you can't see something and it has to be shipped. That is probably the biggest indicator of scam. If its coming from some other state why is it listed as some small town near you on craigslist? Usually when you do some google searching you'll find the same images used over and over from other craigslist scams, as @SpeshulEd pointed out. Many times the wording on the craigslist post are copy and pasted too, word for word, for the same item in many states.