Our family is new to RV ownership as well. Water leakage is THE biggest concern with any class C. I have major rebuild to do in cabover, but ours is a LOW cost 1983 Jamboree with everything else in pretty darned good shape. I am not happy, but live and learn.
Have a shop go through it with a fine toothed comb if you don't know what you are looking for. Get them to put in writing what they did and confirm no water damage. Then pay to have the whole top sealed and enjoy. If you are thinking this could be a long termer, confirm no leaks and think about applying a full roof coating. As I understand it, they are supposed to last upwards of 15 years per application.
Can anyone confirm if you can re-apply if any cracks develop? Personal long term experience with roof coatings?
Jose