Is painting over wallpaper a good thing if you prime first?
Wallpaper paste isn't designed to hold more weight than the wallpaper itself. The primer plus a coat or two of paint will cause it to start peeling. The moisture from the paint may even weaken the existing paste causing it to come off even faster.
There are some insulating wallpapers intended for use as a base layer for paint, but those are sold to either provide texture, such a pho-Adobe, or to provide heating insulation.
If you paint over the wallpaper, you'll end up taking down the wallpaper anyway. My advice is to get a steamer, a wallpaper scraper and take it down and do the thing right. You'll regret it otherwise.
Painted over wallpaper. Learned the hard way what a bad idea it was.
UPDATE: On December 1, I was notified that my answer had been chosen as the "Best Answer" with two whole votes.
Just to be safe, I posted a couple of the useless, mindless drone answers Yahoo loves so much.
Q: What is the best way to heal a broken heart?
A: Time is the only balm for a broken heart.
It's almost lame enough to be a line in a country song.