I see your point, Ron. After my addition was built and the rest of the house looked spectacular, I was still left with the old master (now a super nice guest BR) which had not been touched. The walls and ceiling were in horrible shape. So much so that I was thinking it may require new sheetrock. My painter came in, assessed it and told me point blank - there is no amount of paint to fix this. He said the way to go was to skim coat the entire room (20x15). So, he started by checking the drywall adhesion all around including and especially the ceiling. Turns out he used about 200 screws in various places, most in the ceiling. Then applied the skim coat which was 3x5 gallon buckets of drywall compound that he mixed down with water to make it easier to spread out. Finally, he did some light sanding and painted it. I never thought it was possible, but that bedroom looked like brand new and still does to this day.
-Stu