You have to factor in the cost of an accident from cleaning them. What that really means is learn how to clean them without having an accident, and don't overclean them. In the future, drones will do this. For now, I'd like to know best practice, since I have trouble with it. In my area I don't have dust but in the Central Valley they sure do. I have moss! (It's humid here.) I generally don't overclean them. When they look terrible, I'll make sure I have some sort of accident-free session of doing something to clean them. If I lived where it was dusty, I'd look for some way to blow or rinse the dust off.
I've heard that using chemical soaps might wash off the anti-fogging and anti-growth coatings. I would be interested in recoating systems because of that potential, but not if it's just a scam, so I'd want to see tests of how effective recoating systems are. I don't presently know of any recoating systems.