Got in my visit to another dealer today. I didn't get blown off, was there for almost two hours. I did ask if the salesman had ever owned an RV - thank you for suggesting that! No, he had never owned one, but he was "allowed to drive the rvs around." That explained why he wasn't knowledgeable about the systems, and we didn't talk about that much, it was mostly the expected pitch. However, I did learn some valuable information about types. I saw a couple of small A's, I didn't think they came that small. And I went in a B, too narrow for me to live in. Then we got into the B+, C thing and there seems to be a lot of confusion in general about this term. B+ seems to be a variation on the C, not the B, go figure. But I got the feel of a lot of different kinds of space, so that is far more helpful than looking at pictures, and I'll know more what the layouts represent going forward. He did answer questions about tires, but I don't think he had a lot of knowledge beyond the dealer lot.
I got encouraged to get a warranty for anything I buy, and to bring the rv in a couple of times a year for check-ups (@$120/hr). I'm thinking I would keep money aside for emergencies, look hard before I buy, and learn everything I can about operation, maintenance and systems.
Thanks for all your "what should I ask" comments. This guy didn't have all the answers, but I was more confident and think I got everything out of this trip that I could.