I admit, some wallpaper is hideous, outdated, or installed improperly. It also depends on how much wall paper is covering the walls. Buyers can usually deal with paper that is subdued, installed properly, and not covering every inch of wall. However, I've shown homes where even the ceilings are covered - Ugh! Some buyers walk away from homes that are wonderful in every way - thinking they do not want to waste their time or their money removing it. As a seller, if you are not in the position to remove it and repaint, then perhaps getting an estimate to provide to would-be buyers would be a good idea. Sometimes, it's even better to just re-drywall over the old stuff. There is a thin drywall that can make the job easier, especially if the home has old plaster walls. I'd never not consider buying a home with wall-paper, but I can see the big picture. Some buyers cannot see the home past the wallpaper.