Air-duct cleaning a rip-off?

Why contractor recommends replacement instead

DEAR BARRY: I recently hired a contractor to clean and service my heating and air conditioning system. As he was doing this, two concerns arose: asbestos insulation on the air ducts and dust build-up inside the ducts.

When I asked about cleaning the ducts, he said that they cannot be adequately cleaned and that companies claiming to clean air ducts are just ripping off their customers. He recommended installing new ducts, rather than cleaning the old ones, but this would be very costly. Then, as a side note, he mentioned that my ducts are insulated with asbestos — and this has me worried.

The insulation that is on the ducts is metallic in appearance, and I always heard that asbestos is white. What should I do about the asbestos (if that’s what it is) and with the dirty ducts? –Heather