There are scams on Craigslist same as with eBay and lots of other places including RV dealers. Usually it is someone selling something at a price that is much too low compared to similar items being sold and so people will take a chance when they should walk or run in the other direction.
If someone wants a deposit that should set off alarm bells that the seller is running a scam. This includes RV dealers as many have shut their doors in past years and when they go out of business the deposits that they have taken for RV's are seldom returned to their customers.
If they want to meet you at some location that is out of the way like a Wal-Mart parking lot that too should be taken as a sign that something is wrong. If they will not let you take it to a place to have it professionally inspected it is also a sign that it is a deal you do not want to make.