The smell is usually what tips people off. If it hits you every time you open the basement door, you have mold, humidity, or both. Other things worth paying attention to: white chalky patches on the concrete, which is moisture wicking through the foundation itself, condensation on pipes and ceiling joists during the summer, dark staining low on the walls, and any memory of water coming in during spring runoff or after one of those late summer thunderstorms that dumps an inch in twenty minutes.
Finished basements are the worst offenders because the mold has drywall, framing, and carpet to hide behind for months before anyone notices. Mapleton has its own set of problems here. We sit at the base of the mountains, so snowmelt coming down off the bench saturates the ground every spring, and a lot of the older parts of town have a shallow water table that people do not find out about until their sump pump gives up. Utah soil is heavy clay in plenty of spots too, which holds water right against the foundation instead of letting it drain away. The dry air outside does not help you much when the water is coming in from below. If your basement has felt damp for as long as you have owned the house, that is worth looking into now rather than after you replace the carpet.
