This depends on how dirty they are...if they are clean then it is a scam...if they are dirty then it will help with indoor air quality. A clean duct will "flow" better. If you are diligent about vacuuming, change your filters regularly, and don't have pets..then your ducts my be fine. An inspection will determine if it is needed.
We were in the same boat and finally last year I caved and did it. Hired a reputable company and was very pleased. They had cameras on their equipment so it was quite clear what they took out !! I have to say it really reduced the amount of dust flying around too!
Yes and no. Duct cleaning can be important if you suffer from unexplained allergies or your duct system is filled with cat and dog hair. But its very unlikely it will do anything to the air quality of the home as the dust in them is not blowing out. If it was the duct would be clean.
The EPA has published this information to determine if indeed this is something you want to consider. http://epa.gov/iaq/pubs/airduct.html
If you have steel galvanized ducts in most cases mold will not grow. The galvanizing process when it becomes damp releases chemicals that prohibit mold development. And if no moisture is present mold cannot grow either.
The really only reason to do this is if the house was really dirty from past owners, has cat and dog hair present, you suffer from allergies, or you just had a house remodel project and the house became dusty as a result.
You should however clean the fan system in the furnace or air handler. And the AC coil should be cleaned as well. Most duct cleaning guys do not do this as they require a license to work on the cooling side of the system. Contact your HVAC people and ask them to clean this part of the system for you.
A good filter system and sealed duct system goes a long way in keeping the house clean and prevents dust from collecting on the cooling coils located within the cooling and heating system.
All which your heating professional can provide for you.
Thanks for all the answers.
what a greatr site
Having mine done made all the difference in the world in cutting back dust & allergy problems. Well worth the cost to me.