This Duct Cleaning Company advertises a low $39.99 then tries to convice you to paymore when they arrive. They multiply the number of returns at your home by the low attractive offer.
On top of that they hook up their loud equipment after little "preping". The equipment is actually not sucking out anything, but making a lot of vaccum noise. I caught this deception by being very curious and observant. It seems many of the duct Cleaning Companies are doing the same smoke and mirrors Scam.
Pam Zeckman of one of Chicago TV News segments confimed my suspicion by busting such a Company.