Megan and I are working quite hard to get our new house ready to move in. So far, we've tackled the family room by removing the wallpaper and residual glue. Zinnser DIFF has been a lifesaver for us. We started out by using a squirt bottle and moved up to a gallon jug applied with a paint roller. After rolling on, it seems to take about 5 minutes before the glue begins to come off using a putty knife. Hard work with a sponge gets the remaining bits of glue off.
The next question: To Skim Coat or Not?