Sometimes, mold problems are immediately apparent. If you've recently experienced a major flood, there's a good chance you'll spot mold growing on walls, ceilings, fabrics, and other affected areas. While these situations require immediate professional remediation, many mold problems won't make their presence known quite as clearly.
In these cases, you may only suspect that you have a problem based on unusual odors, or you may discover some mold when cleaning damp areas, such as under a sink.
If your house smells musty but you can't locate the source, then you should take a look down in the crawlspace.
Especially in areas with high humidity, mold can grow down in the dark void below your home, and eventually you will be able to smell it inside the house.
Not only does mold smell bad, but it can also lead to structural issues for your home and health issues for your family.