The answer to 'why is my humidifier smells bad' is that a smelly humidifier is often caused by bacterial growth or mineral buildup in the unit. This can happen when the humidifier is not cleaned and maintained regularly. The smelly odor is a sign that the humidifier needs to be cleaned and disinfected.
Symptoms of a smelly humidifier include a musty, unpleasant odor coming from the unit. This is usually caused by mold, mildew, or bacteria that have built up inside the humidifier. If the humidifier is not cleaned properly, these contaminants can circulate through the air and potentially cause health issues.