PopsRV is an online broker.
I considered an RV that they had listed, but they wouldn't talk about it through email. I had to call an agent, but he didn't really know anything about the RV besides what was in the listing, he was in an office far away and had never seen it himself.
The way they explained it was that I had to extend a formal offer, and only then would I be able to see it in person, take it for a test drive, inspection, etc. I'd have a certain period of time when I could rescind my offer. If I accept the unit (perhaps asking for repairs, price reduction, etc), we'd proceed to closing and finalizing the purchase.
It sounded pretty much like doing a private party sale, but with more steps. I opted not to proceed.