This link discusses the 2 types of vinyl wallpaper and the pros and cons of painting it:
First you need to be sure the wallpaper is in good shape and not lifting or peeling. Clean it well and paint with a good primer. After that, you can paint it any color you want.
I would remove the wallpaper first. I have seen painted walls over wallpaper and the seams always show through. You would have to spackle the seams and sand. Vinyl would have to be sanded to apply paint that would adhere well. So with all this work, I would just remove to get a nice wall to work with.
Removing wallpaper isn't that hard:
Use a scoring tool that you can use in circular motions. This will score the wallpaper and cut it into tiny little holes all over. Then you get a wallpaper dissolvant liquid that gets smeared on top of all the holes so that it soaks in. All of this is at Home Depot. Run the hot shower for a bit in a bathroom....would work well to loosen everything up. Then peel off the paper. Good luck!
These suggested techniques may help:
Hi Nikki, it will really depend on what shape the wallpaper is in. If it is adhered well to the wall with no missing or lifting bits, then you can paint it. Just remember that them moisture from the paint may make it start to peel or lift so you may want to test an area first if possible (around an edge or seem so that you can see if it will start to lift). If no, you can prime and paint it without any problems.
Nikki: maybe this will help
I would not paint over wallpaper.
Hi Nikki: I painted over vinyl wallpaper in my kitchen several years ago and it has held up great. Although it does not get the steam that a bathroom would get from showering. If the wallpaper is in good condition, no tears, seams together, then you could try painting. But there is a very easy way to remove wallpaper. Get a tool called paper tiger at the hardware store, it is only a few bucks. Score the wallpaper, then spray with fabric softener mixed with water.
About 1/2 and 1/2 mixture. Let the softener stay on for about 10 minutes, Use a plastic scraper and the wallpaper comes right off. A plastic scraper will not hurt the walls.
It took me a total of 45 minutes to remove wallpaper in the entire bathroom and the remaining glue. Most of the glue came off with the wallpaper. If not combine hot water, liquid dish soap, and a tablespoon of baking soda in your bucket. If you find that the glue doesn't come off easily when the solution is applied to the walls, add vinegar to the mix—about 1 cup per gallon of water.
When dry you can prime and paint. This is a better solution than painting over it in a bathroom.
There is paint over almost all the wallpaper in my very old home. You cannot see the seams at all and it hasn't peeled in the almost 20 years we've been here. I would recommend removing the paper if you can, especially in the bathroom where humidity can be a factor. If you choose to paint over, I would consult an expert at a local paint store to get the proper tools and primers.
Thank you all so much for your comments.