Delamination is a great indicator of water intrusion. If I were buying again, I'd avoid any RV with delamination. Some delam is caused by the sun heating the laminate and causing the glue to let go - especially if there are dark-colored decals/paint on the area. But I think that issue has been largely addressed.
A rotted RV is a headache, from mold causing allergies to structural integrity. I have to take Allegra every time I use our RV because of this. When shopping, believe your eyes and your nose. Also go around the inside and outside of the unit, pushing firmly on the walls in suspect places - corners, along the roofline, under windows, feeling for softness.
Steve