If you have an older home, which most of you do, the likelihood of getting all the dirt out of the system without some kind of camera or video equipment is highly unlikely. I had Duct Hunter out to my house a few years ago. I went back into my house system with video equipment 2 years later and looked at the ductwork. It was filthy! I am thankful that I decided to get the house cleaned again. This time with the aid of cameras to make sure the ducts were clean.
I have found that the older homes here in Fostoria usually have a floor return system and most of the supply ducts are on the 1st floor of the house. On two story homes there is usually some odors, fungus and mold growing in the duct work. Cleaning the return on the older homes can be a bit more challenging for any system, but with Roto Vision, you have a 95% better chance of getting all the dirt out of the system.