During the wallpaper removal process with a steamer, don't heat the wall too long if you have paint underneath the wallpaper. It will steam off some of the paint and add to the disaster. Feel free to steam more if there is open drywall under your wallpaper. After the wallpaper is removed by whatever means... professionals do a final "Skim Coat" which means applying a very, very light coat of Joint compound with a 5" drywall knife. Your skim coat will sand smoothe quickly with little labor leaving a beautiful wall ready to paint.