Henry is right. You should wash the wall clean of the glue-residue.
If you use a mixture of DIF and water, you'll be sure to rid the glue. Follow the directions to the 'T'. FWIW, washing the walls is the official final set when removing wallpaper. Use natural light if possible to see how the walls look before AND after you wash. I suggest you use one of those large car-wash sponges to do this. It goes much better. You can find them everywhere especially in Pep Boys, NAPA, K-Mart, etc., etc.. DO prime before you paint.