No, to premixed mastic in wet areas. It is ok for dry areas, such as an area of backsplash where there's no water or sink. I would not want it in my bathroom under any circumstances because of the characteristics of mastic and the damp conditions bathrooms need to tolerate.

Do you need to replace the tile in the area you are referring to? I wonder if you can just replace the drywall and paint with a good quality bathroom paint. If this wall is in the shower, of course that is not a recommendation. But bathroom walls don't need tile in the non wet walls. It is an esthetic thing.

Bathrooms are humid, so install a fan if there isn't one, and if there is, make sure it is venting the moisture properly to an outside vent.

I would be concerned that if the dry areas of the room have this type of tile installation, that the shower area may be incorrectly installed.

Thanks. These tiles go about 3 feet above the bathtub and around to where the sinks are. The tub is separate from the shower area.

The tub has similar tile on the platform around it. That tile is horizontal. Some of it is loose, but being horizontal it isn't going to fall.

I could probably take the wall tile off and have a plasterer redo the drywall. We have redone drywall in other rooms with good results. Probably a short 2 inch tile at the bottom for minor splashes.