The answer to 'why is my steam cleaner moldy' is that steam cleaners can develop mold and mildew if they are not properly cleaned and dried after each use. Moisture left in the machine can create the perfect environment for mold and bacteria to grow.
Some common causes of mold in steam cleaners include: leaving water in the tank or hose after use, not thoroughly cleaning the machine, and storing the cleaner in a damp or humid area. Signs of mold include a musty odor, visible growth, and poor cleaning performance.