I would think that the most damage to an RV can come from lack of use rather that constant use, and the miles on the wheels would have little use as a measure of any RV's actual condition. Certainly, around here many rigs are lived in full time all year round in RV Parks..(yes, this is Canada), but winter conditions can be horribly dismal, pouring rain and blowing, then freezing after rains sometimes. The most dangerous of all possible environments. As medium size stores fall under the onslaught of internet buying nowadays astute buyers of empty buildings have been turning them into RV storage warehouses all over town. The one thing to watch out carefully for in RV purchase: condition, condition, condition!