well, i'll tell you that having wallpaper removed (which was worth every penny) reveals a lot of flaws in the walls.
Just had to do this in our new to us old house. two rooms were UGLY wallpaper (dark red in one, bedroom, ugh) and had it removed. plaster walls (old house) and flaws around the new (90's?) windows and such which were not visible until the wallpaper came off.
the drywall guy wasn't cheap, but he came in, skim coated it, fixed the issues and then put on heavy texture (to match the rest of the house) and it looks amazing. Also, drywall guys (and painters) value cash deals, just saying.
was it cheap? No, but drywall work is also worth every penny (more art than science) and it looks like it did when it was a new house. It's also done forever, i never have to futz with it again, the flaws are fixed and all i have to do in the future is just paint.
over 20 years that 4 grand (total, painters, removal, drywall work) is a nothing burger.