Our house had wallpaper in the entryway that had been painted over. When we tried to take it off it peeled the top layer of paper off of the sheetrock so that now there is only a thin brown paper layer over the sheetrock core.
Question: Can I sand, prime, texture, and paint this without too many problems or would it be better to just replace the drywall?
Each and every wallpaper removal is a new experience no matter how many times you do it. That being said, all is not lost.
How much "mud" work is required depends upon the severity of face paper removed. Usually if the brown spots outweigh the white spots we will "float"the entire wall.
"Floating" a wall consist of using a good quality sheetrock mud and applying a thin coat to the affected areas. Allow to dry, sand and reapply. You will notice during the first coat your knife will pick up a fair amount of trash. Don't worry too much, just pick it out of the mud and keep going. This will be handled when you apply the second coat of mud. Allow this coat to dry overnight. Sand this coat and apply a drywall primer. allow this coat at least 6 hours drying time. Usually we have areas of mud which need to be touch-up at this point.
Quite often for this last application of mud, I will add some chalkline dust to the mud so we know where to sand as the primer and the dried mud are the same color
Spot prime the touch-ups and then apply 2 coats of your finish paint, sanding between coats.