I am in the same boat as you are, the whole house had wall paper, and in some rooms, there was more than one layer of paper. Even if you put a skim coat of mud over what you could not get off, you will most often find that what was left will draw the moisture out of the mud and you will still have the same problem, although now it has penitrated and will be much easier to scrape off, just be sure not to damage the drywall. All I did was use a spray bottle of water, peeled away what I could, which left enough for the water to soak in, and worked other areas,then went back and scraped some more, soaked , and the process went quick. Keep in mind this was wall paper put over a wall that was textured,over drywall a skim coat, and or shoot a textured finish over a small area,do the knock down, let it dry and then apply some paint and see how it looks,if this is done over the problem area and turns out ok, then chances are the rest will turn out just as nice.
CAP Home Improvements