yes get a good company and pay the price, I found so much dust and dirt and wood and paint chips and bugs and even bottle caps in my ductwork. I hired a major plumbing company who cleaned ductwork and i will say they did an excellent job cleaning my vent. they did miss one point in my ductwork because i still started to see dust all over my furniture and i realized that my retunduct work that was connected with a piece of sheet metal beam which was 16" across , the contractor that built my condo used a 16" wide sheet of sheet metal to connect the vent system to my return for the air to return back into my condo. The contractor should have built a 8" x16" square duct by 6 feet long to connect my intake to my return instead of using a sheet of sheet metal 16" wide by using two 3' sections by 16 inches wide. That was a shor cut which caused a major problem fir me.
I have a white gritty dust throughout my whole house. Dust and it comes right back. We have central air. In 2013 had all the air conditioning tubing in the attic replaced. Old ones were completely clean. Why?? Thought dust would be in there. Put everything in plastic containers. Furniture everything is always covered with this. Problem is always there year round. Furnace people said it is not coming from furnace. We built house in 1971. Only started with this @ 19 years ago. Thinking when air conditioning went in. We cough all the time and sneeze. I do not have friends come here because I hate how dirty my house looks.
You may consider having your air ducts cleaned simply because it seems logical that air ducts will get dirty over time and should be occasionally cleaned. Provided that the cleaning is done properly, no evidence suggests that such cleaning would be detrimental. EPA does not recommend that the air ducts be cleaned routinely, but only as needed. EPA does, however, recommend that if you have a fuel burning furnace, stove or fireplace, they be inspected for proper functioning and serviced before each heating season to protect against carbon monoxide poisoning.