not a professional painter in the lot. Try DIF, wallpaper adhesive remover, or Downy fabric softener. Have enough patience to allow it time to work. Follow directions on bottle of DIF. (wet down entire area, wait 15 min. repeat. then work methodically on a section at a time) After scraping an area, semi-clean of paste, use sponge )industrial sponge) and fresh solution to scrub off residue. Wash area clean w/ hot water and clean sponge. Stubborn glue is removed in stages. Areas of torn drywall surface must be primed w/a specific product like oil base KILZ or a new product called SHIELDZ (latex based)damaged drywall primer, prior to patching w/ mud or (important*) bubbles will appear. Patch uneven wall surfaces, sand, skim coat entire area w/ thin coat of drywall mud if necessary to achieve smooth surface. sand area, remove dust. prime area w/ flat latex wall primer. Surface is ready now to accept finish paint of your choice. Two coats required for perfect finish.

Next time you think professional painters are overpaid, go back and read this.