When is Air Duct Cleaning not a waste of money?

https://youtu.be/Wga2LsyDdmE Organizations that abide by the National Air Duct Cleaner’s Association (NADCA) cleaning process don’t make air duct cleaning a waste of money. This is because, for HVAC cleaning, NADCA sets the highest cleaning standards.¬† However, due to the lack of a governing body for air duct cleaners, the existence of bait-and-switch scams is explained. […]