still used if painted. the only problem is that the paper tigers teeth might not be deep enough to penetrate the paint and the paper at the same time. Depends on how much paint is on the paper. But, you have alot of hard work ahead of you. Your goal is to saturate the wallpaper so that it will release and you have to go through not only the wall paper, but the paint also.
Do not compromise the thin paper covering of the drywall with deep gouges or you will have to re rock the room also.