First, this company does not seem to know who they are - they are in the YellowPages and use invoices that show "Quality Air Systems", but have uniforms, trucks, and Homestars labelled as "Ontario Power Air Duct Cleaning".
When the labourers arrived, they did not introduce themselves, but asked us to let them bring the hose through the back door. We later found out that the hose had had gas spilled on it from an open gas can and had not been cleaned prior to entering our home.
They drilled new holes in the ducts instead of using the existing, serviceable ones. They also caused minor damage to wall corners and dented our ducts. While they did remove dust from the ducts, they did not use a drop cloth nor cared that dust was spewing out the remaining vents took several weeks worth of cleaning to finally get rid of.
We were upsold on sanitizing, furnace cleaning, and a replacement humidifier pad, but we can't say we got value from it...