We have wallpaper in a 7 X 8 bathroom with one window and no exhaust
fan. We use the stall shower at least twice a day, and have never had a
problem with peeling. The paper is pre-pasted, strippable, not vinyl,
and I didn't use any extra adhesive. I put the first pattern up about
15 years ago, over unprimed new drywall (I didn't know any better) and
I was very happy with it. About 10 years ago we redecorated, and since
the unprimed drywall was fine, I just stripped off the old paper,
painted the trim, and then put up new paper. It's been peel free as
well for nearly 10 years.