Sometimes experience is the best teacher. Our experience with moisture have allowed us to gather a few facts.
Fact One:
If there is enough moisture present within the structure to cause visible problems, there is a source of water intrusion.
Fact Two:
Duct work does NOT make water, therefore should not be considered a source.
Fact Three:
Introducing warm moist air underneath the floor (fan) may hurt more than it helps.
Fact Four:
Beware of folks who are quick to think they see the problem. You must do a thorough investigation when moisture is a problem. If someone diagnosis the problem without going into your attic, under your floor, and maybe even the roof, you would be better off considering someone else to help you.
Fact Five:
Structures with excessive moisture problems will most likely have at least one of the following problems;