Painting over wallpaper is like kiting checks. If you're careful you can get away with it for a while, but eventually you're going up against the wall.
Of course you can sell the place and buy another, but you can't replace your house for what it's worth and anyway the mortgage rates have gone up.
In my case it was an inherited problem to which I contributed four coats. Under those were six more layers of paint and under those was rosebuds-on-gray wallpaper circa 1948. The full spectrum as I recently learned after great effort, was two coats each of light green, lavender, dark green, rose, yellow and pink.
Things had reached the point where the paint would begin to peel in less than a year and the spackled areas from earlier paintings resembled a map of the moon. It was either panel it or peel it.
The classic method for dealing with such a situation is of course the rented wallpaper steamer. But you already know about the accursed wallpaper steamer, perhaps have broken your heart on one, so why am I telling you this? What's new? Well, what's new is a supersonic magic wand that insinuates itself between the paper and plaster and whisks if off.
Or so I was told by a person who is generally considered truthful and who claimed actually to have handed one. I called all the tool-rental places within reach of Arlington on a snowy weekend and they all denied having or having heard of any such device.
I did not go gently into the dogfight. I tried spraying the walls with water. Then soap and water. Then industrial concentrated cleaner and water. Best of all was paper towels stuck to the wetted wall and then sprayed with water from time to time.
But a little doodling with a pencil showed that at the rate I was going my daughter (whose room-of-her-own was the arena) would probably make it from the 5th grade to college before I made it from the door to the dormer.
In the end I rented a steamer, and so will you. And the job won't turn out to be quite the trial you anticipated if you:
Start steaming each section at the ceiling, so the drips run down the wall and soften the paper below.
Spread plenty of newspaper along the baseboard, overlapping the sections. A dropcloth won't serve, except as a base, because it won't absorb the water.
Wash the newly scraped section, and the baseboard below it, while the wallpaper paste is still warm and wet.
Use a six-inch broadknife, designed for taping wallboard joints. The best is a used one that's honed down to a knife edge and whose corners are worn more than its center, which helps avoid gouging the plaster. If you buy a new one, get the best quality - stiff but springy - and hone it down by rubbing it in circles at an acute angle on very fine emery cloth.