KC wrote:

The wallpaper came off easily, in large sheets the way it was put up. The
tan - light brown glue that remained on the plaster walls is much, much
harder to remove. Every wallpaper remover I've tried says to apply the
product then sponge or scrape away the remaining glue. That technique does
not work with whatever is on my wall.

Currently I am spraying a near boiling mixture of 50% water and 50% white
vinegar on the walls and waiting a minute or two, then using an abrasive
wheel in my power drill motor on the walls. This seems to take the residue
off, but the process is really slow. In addition, this still leaves small
amounts of the wallpaper adhesive on the wall. Which is a problem, because I
have been told the surface must be completely free of the old adhesive to
ensure that any paint applied to the walls will adhere properly.

Any suggestions or methods to try in removing this past would be
appreciated.

Assuming it is wallpaper paste and not that somebody used some
non-water-soluble something to put it up with, as John noted if you have
a really heavy layer and large area, the steamer may well be worth
renting...

It's possible to rig up a steamer yourself, but much more
awkward---don't be over cheap here, is my recommendation.