I hired a contractor to update my bathroom. The walls and ceiling was repainted. Now I am constantly wiping down the walls and ceiling with bleach because of the stains and mold. Is it possible that the contractor did not use the right paint? Should I just repaint or place the drywall?
Re: moldy mess
Paint won't cause the walls to mildew, moisture does that. Paint that contains mildecide can help, but without rectifying the moisture problem the mold will continue.
By chance was an exhaust fan installed during this renovation?
Re: moldy mess
Spruce is probably giving you a good clue as to what is going on, especially if you did not have this mildew problem before. I have seen similar problems more than once where a vent was improperly installed or re-installed after renovations. The duct connections must be taped tightly shut and the duct should vent directly to the outdoors, or at a minimum, dump out right next to the attic vent high in the attic. If you did not have a vent installed, do so!
As to what paint should have been used: All premium interior paints contain a mildecide. Traditionally, baths with showers would be given a coat of semi-gloss paint. Semi-gloss is much more resistant to moisture transmission, and oil paint much more so than acrylics/latex paints. I know of no flat paint which is recommended for baths. After determining whether or not your exhaust is involved, I would once again wash your walls down with bleach. A 1 part bleach to 3 parts water mixture is normal. It is imperitive that the mildew spores be dead before you re-paint! Mildecides in the paint will retard mildew growth, but not kill active spores. Many manufacturers have paints specifically labeled "for baths". Zinsser has one. All of Behr's Ultra line of Eggshell sheen and above are rated for baths also.