Re: Tiling a shower ceiling
You can tile a ceiling with no fears, just a few steps need to be taken;
Prepare the surface for tiling. If its has many coats of bad paint, you'll want to replace the drywall. If the ceiling got wet with a lot of condensation or steam or splashing, then replace the drywall with cement board.
Coat the surface with Hydroban, HydroGuard or RedGuard, following the directions.
Using a powdered thinset you mix with water, install the tiles. They won't fall down when set properly. NEVER ever use a premixed (mastic) thinset or grout in a wet area such as this. When it gets wet it softens and returns to goo.
Grout the joints, caulk the edge joints where the ceiling meets the walls using only 100% silicone caulking.
Why are you getting so much water there? need better venting?