Some signs are obvious, like water pooling on the floor or running down the walls. Others are less noticeable, so you’ll need to pay attention. Increased mold or mildew growth, strong musty odors, and white residue on the walls are all signs of excessive moisture. So are bubbling wallpaper, peeling paint, dry rot, damp spots on or cracks in the walls or floor, and rust on appliances and furniture.