I just learned a trick that has worked like a charm. I have a home with 40 year old wallpaper, original from the builder. The walls were not primed prior to the paper- straight drywall. The trick?- In a regular cleaning bucket or sink pour one capful of fabric softener into generously warm, not hot water. Spong onto wall into area of about a yard at time and wait 30 seconds. Using a putty knife (plastic knife of 3 or 6 inches works best) gently scrape away the glue. This really works. Prior to this I was using a commercial product and a steamer. This was infinately better. Just keep plenty of paper towels on hand to clean the putty knife!