Water on Bathroom Walls
Bathrooms with showers often have moisture that collects on walls and surfaces. Over a period of time this can lead to mold. If you have mold on your bathroom wall it means that there is not proper ventilation in your bathroom.
Most bathrooms have a ceiling fan to remove extra moisture in the air. Turning on your ventilation fan should help remove the moisture in the air before it settles on your bathroom walls. It can also help to leave your bathroom door open when not in use.
If your bathroom has no vent fan, you can take a portable fan and aim it into your bathroom, and then turn it on for 5 or 10 minutes after you shower.