Duct cleaning is a band aid, like washing you hands is. Under your description, why wash your hands more than once? If it gets cleaned once, it shouldn't get dirty again. Well that is, unless they touch something dirty. Keeping your hands completely clean is virtually impossible. Same as keeping dust out of your home. You clean your ducts and over a 3-5 year span they get dirty again. Also, duct cleaners are not licensed but should be certified by NADCA(National Air Duct Cleaning Association).
I'd have to disagree with all of your statements. Not only are they derived from no experience in the field, you are missing keys facts. Ducts even if air tight will get dirty. If they are not getting dirty, it means they are not working. Your returns side of the duct work is always under negative pressure when the system is operational.Therefore it is always drawing air in. Seeing how dust is made up mostly from dead skin humans shed daily. Around 1.6 Pounds of skin a year per human. Living in your home anything that is air born will be drawn back towards the cold air returns. That is what they are designed for, to draw stale air back to the system to be filtered and sent back through the house.Homes with carpet will actually have cleaner duct work than home with all tile or hardwood. This is because carpets hold onto dust particles and you vacuum them up. Whereas on hardwood or tile, dust can run freely back to the returns. Even if a duct system was sealed 100%, which is next to impossible to achieve 100% would still need to be cleaned. The cleaning may only have to be every 7-10 years for example. Most homes require every 5-7 years. And that's if it was done properly the first time. If you constantly hire people that have no or minimal knowledge of duct cleaning, You home would require cleaning more often. Every 2 years. That's a trade secret, The longer they recommend before the next cleaning, the odds are they did it right. That's not to say there aren't people that lie, because there are. Just have your duct cleaner take pictures before and after cleaning. Not just an outside view. Get in there, picture entire joist liners, Whole main runs and even long round pipes. Also it helps to have a company that guarantees their work. If it's not done right, they will come back and do it until it is. Most companies that do this make sure it is right the first time. Your not getting paid to do the job twice.
If you don't agree with duct cleaning, fine. If there are some things that HVAC people can do to make the system need cleaning less often fine, but to suggest that I need to GO TO JAIL????? If you need to knock others to make yourself look better....... If duct cleaning is such a scam, why are their governing bodies like NADCA (which I do NOT belong to),several manufacturers of equipment, and national restoration franchises (I'm not a franchise either) who provide this service? I guess the whole world is stupid and only HVAC people are smart. I suppose I am scamming them when I clean puff backs, water damage, fire damage, and clean their carpets too? Or did I wake up one morning and say "ya know, it is great to be a hard working, honest owner operator, but I would love to provide a service that unlike everything else I do is a con and rips off the 90% referral business I busted my butt to earn"
I hired duct cleaning company out of "Service Magic" website. I did not realize the name of his company was Duck cleaning of Central Florida...that should have given me a hint.. The guy did a very poor, incomplete job, and ruined a closet full of clothes when he sprayed up to clean a vent instead of taking it down and cleaning it outside. He left me with more than 1/2 dirty vents and ducts, did not do the air handler in the garage and failed to fog the system. He spent 6 useless hours at my residence and now his insurance is denying coverage..very disappointed in Service Magic....
The amount of debris or mold present in your system could certainly ratchet up the overall price. The cost of mildew removal is around $0.07-0.08 per square foot, on top of your initial cost, according to Blue Book. Removing these elements involves added time, special equipment and even special chemicals. In fact, you may be referred to a specialist if mildew and mold is too severe.
You should be aware that although a substance may look like mold, a positive determination of whether it is mold or not can be made only by an expert and may require laboratory analysis for final confirmation. For about $50, some microbiology laboratories can tell you whether a sample sent to them on a clear strip of sticky household tape is mold or simply a substance that resembles it.