First Time Buyers (Used)

Thanks for all the helpful words of wisdom, i am very careful when buying a car but don't know enough about motor-homes. That's why i am here asking advice. I am finding this forum VERY helpful. Like i said i have met a couple of Dealers already but i fear they know a rookie when they see one. They all seem to tell me that they have a tech. that has gone through the whole coach already lol. I will defiantly look into how to read tire dates (Great advice thanks) and pay attention to dry rot. I think i know what the previous poster is saying when he states "Best time to look for a used RV is when its raining." You can prob. see leaks better but i was told NEVER buy a used car in the rain (It always looks better). I do need a motorhome that will stay cool inside, Is there a better system to look out for as far as Air?? Do they all have heat?. I am NOT looking to camp here in New Hampshire in the Winter in fact that will be when we go to Flordia or someplace warm. I am excited about buying a Motorhome but at the same time scared of making a bad decision. Thank you ALL. Steve and Carol