Facepalm

We had a similar problem with an upstairs bathroom. We ran the fan constantly, but still mold was everywhere. You could see where it was painted over in the past with a different color paint. The owner's handyman friend decided that replacing the fan would help. When he was removing the old one, we realized that there was no ductwork attached to it. The fan was just sucking all humid air into the space on the other side of the bathroom ceiling.