We had a problem with wallpaper backing “not” coming off with any product, even DIF, because the paper had been applied directly to the drywall. We rented a steamer and after “MUCH” work it did come off, however, no matter how careful you are the drywall does get marred. We had to spackle heavily, sand, primer, texture, then paint. Although this isn’t the most common thing you’ll find, it is possible to get past and is better for resale purposes as posted earlier. You should easily be able to tell what’s behind your wallpaper…just pull up a small piece in the corner and see what’s there! Good luck.