We looked into buying a rental (not from Cruise America, but from a local dealer that rents) and decided against it. Here were our reasons.
1. The units are all stripped down. In an effort to keep them idiot proof, most rentals don't come with awnings, antennas, or anything else that a novice driver would overlook and drive off with not in its correct position. You'll either have to pay to have these options installed if you want them (adding to your overall cost), or do without.
2. The units are high mileage. Without complete service records (which our dealer could not or would not provide), you're taking a big risk. If it's been well looked after you might be okay. If not, you're going to be looking at engine problems and new tires ($$$$) in short order. The same holds true with the generators. If they've been used a lot, yo may need to replace. If they haven't been used hardly at all, you've got another set of problems getting it cleaned up and ready to run.
3. The interiors are worn. The units we looked at were all very worn inside. Carpeting/vinyl all would have needed replacing and there were dings in the walls, etc. Don't get me started on the mattresses. All can be fixed, but again it's adding to your base price.
4. The smell. You're not supposed to smoke in the rentals. Yeah, right. You're not supposed to have pets in the rentals. Yeah, right. All but one of the rentals we looked at smelled terrible. And then there was the one that I presume had been used on a fishing trip and the fridge never cleaned out.
5. People don't know what they're doing. Most of the units we looked at it was easy to see that the renters had no clue. The handles on things like the black tanks were warped or broken. The switches on the fridge to go from gas to AC looked like they'd been pushed a million times. The dinettes were almost always broken from people trying to put them up and down incorrectly. And on and on. I don't know how much of it was simple disrespect for a rental and how much of it was people just not knowing how to make things work and applying too much force when it wasn't necessary.
6. The roof. The units we looked at had some roof damage. I don't know how much of it was from the dealer not doing good maintenance and how much was from renters running into things or going up there in track spikes or what. But some patching would have had to be done.
We ended up buying used, but form a private seller who had all the records on the unit and had kept it in pristine condition. We still saved a ton of money over new, but had very few problems.