If you own a digital camera, take a minute and stick into the register and take a picture. If you see white fuzz everywhere, lint or hair, your overdue for air duct cleaning, but I can help. It's almost time to turn on the furnace. Have your furnace inspected and cleaned twice a year. In the fall and in the spring before you turn on the Air conditioning.
I have seen a lot of dirty air ducts. I will tell you how to keep your air ducts cleaner once you get them cleaned out. There are some things I can share that will prevent the dust from returning.