Almost every wallpaper removal that goes badly goes badly the same way: the paper comes off, the wall looks clean enough, and paint goes on. Weeks later there are streaks, shiny patches, and small bubbles that were not there on day one. That is old adhesive, reactivated by the moisture in the fresh paint.
Wallpaper paste is water-soluble by design, which is what lets it release, and also what makes it come back to life under a waterborne coating. Getting it off means washing the wall repeatedly after the paper is gone, and then washing it again, until a hand run across the surface feels like drywall instead of anything slightly tacky.
The second common problem is damage to the wall underneath. On drywall that was never primed before it was papered, the paper is bonded to the facing itself, and pulling it takes the top layer of paper facing with it. That is fixable, but it has to be fixed properly: the torn areas get sealed, then skimmed with joint compound and sanded flat, or the texture difference shows through every coat you put on afterward.
Layers complicate everything. Older houses in Delphos, Lima, and Columbus Grove often have two or three generations of wallpaper, sometimes with a coat of paint over the top of them. Painted-over wallpaper has to be scored so moisture can get behind it, and each layer may release differently. This is worth knowing before you start, not halfway through.
The last step is the one people skip. Even a genuinely clean, repaired wall should get a sealing primer before color. It locks down any trace of residue, evens out the absorbency between the skimmed patches and the original surface, and gives the finish coat something consistent to lay down on.
Done in that order, score, strip, wash, repair, skim, sand, prime, and then paint, the wall reads as one flat surface and nobody ever knows there was wallpaper. Done in a hurry, it announces itself for years.