Filter Odor & Maintenance Guide: Smell, Airflow And Replacement Tips Filters are used in many home appliances to help manage dust, particles, moisture, odor or residue. Over time, filters may become dirty, clogged, damp or less effective. This guide explains why filters may smell, why airflow becomes weaker, when cleaning is enough, when replacement is needed, and what buyers should check before choosing replacement filters or maintenance parts.