I'm wondering if it's worth the money ($300+ quoted) to have our duct work cleaned out; does that really work or just create more mess by stirring things up? I seem to be constantly battling high dust levels. Due to allergies, I use a high quality furnace filter and replace it every 2 or 3 months. I also put cheesecloth over the registers to catch some of it. But I'm still seeing what I feel is excessive dust, and am wondering if it's blowing out of the duct work. It seems to be worse on the lower level, so the only conclusion I can come to is there are monstrous dust bunnies that have settled into the lower level duct work. (Our house is 30 yrs old, and we put in a new furnace when we bought it 5 years ago)Thanks for any thoughts on this! -Kathy