Watch: decades of dust removed from air conditioning ducts

In this footage, we see tubes of dust pulled out from air-conditioning ducts like giant playdoh snakes: "there was too much to vacuum, so I reached in there and pulled it out with my hands."

Come for the dust tube, stay for The Whiskers.

Duct Heroes is an Illinois-based air duct cleaning company.  Most houses they clean have never had their air ducts or dryer vents cleaned before.  Ahmad Adas shows how he professionally deep cleans the air vents in a house that he suspects hasn't been cleaned for 100 years.

"Most of it is human skin cells," says Ahmad. "Pretty gnarly!"