The honest answer: it depends on contamination
Duct cleaning is not magic, and any company that promises dramatic energy savings on every job is overselling. The honest answer is that cleaning is worth it when your ducts are genuinely dirty or contaminated — and not especially worthwhile when they're already clean.
Studies show heavily soiled duct systems can lose 25–40% of their HVAC efficiency and continuously recirculate allergens, mold spores, and dust-mite debris. In those systems, cleaning produces a real, measurable improvement in airflow and the particle load of your breathing air.
Clear signs it's worth it for your home
Book a cleaning if you see dust puffing from registers when the system starts, smell a musty odor when the AC runs, spot mold near vents, have allergy flare-ups you can't explain, or simply haven't had the ducts cleaned in more than five years. Recent construction or a new home you've never had inspected are also strong cases.
When you can reasonably wait
If your home is sealed well, has had regular filter changes, shows no odors or visible debris, and was cleaned within the last few years, you can usually wait. A reputable contractor will tell you that honestly after an inspection — which is exactly why an inspection-first company is worth more than a flat-rate phone quote.