On a recent call, a client had a water leak under their sink that went unnoticed due to cleaning materials obscuring the view. It was not until they smelled something that they began the hunt of what it could be. By the time the leak was detected, the damage had been done. Mold had grown on the wood and drywall!
Periodically check under your sinks for signs of water leaks. Mold needs moisture and food source to grow. Eliminating moisture is one of the keys to a clean environment.