Run your hands around the walls after a good rain near where the roof and walls meet, around the ceiling by every roof vent, under windows, around slides. The feeling of wetness compared to places on the walls and ceiling where the underneath is dry is very apparent. Pristine condition means nothing if water has crept in. Look at the roof along all edges, look around windows and doors on the outside. There should be evidence of re-caulking very apparent by now.
Mike
2012 Winnebago Impulse Silver 26QP
2005 16.6 Double Eagle
2018 Jeep Wrangler JK
previously Snowbird Campers,
Triple E Motorhome and Fifth Wheel