I think everyone who keeps chickens long enough will eventually get ectoparasites like mites, lice, etc. I've had a real problem with my feather-legged breeds like Buff Brahma Bantams. So much so that I have all but phased them out of my coop in favor of Wyandotte Bantams (a clean legged breed). Treating your birds and your coop are quite different issues. Since I still use the tried-and-true method of bathing the birds and applying "Vet-RX" or some other oil-based remedy, I will focus on cleaning the coop, or barn, in my case.
My barn has a gravel floor covered with bedding. It is impossible to remove all the shavings, straw, and shredded paper I have put down for the last ten years or so. You can't rake, shovel, fork, or scoop the stuff off the floor. I admire those of you who have concrete floors that can be cleaned easier. Here's what I have to do to "de-bug" my barn and roosts --
I remove all chickens from the barn and treat them as described. I close all doors to the barn to prevent them from coming in while I work. I take a 20 gal. hose-end sprayer and add the appropriate amount of pyrethrin or peremethryn barn and stable spray concentrate. Starting with the farthest, uppermost corner, I spray the daylights out of all surfaces. Gravity helps the process. When I reach the door (walking backwards) I stop spraying, exit, and latch the door. About eight hours of saturation does a good job of killing and repelling almost all insects. Before I open it back up to the chickens that evening, I spread a healthy layer of cedar shavings. Cedar has some repellent effect on mites and lice, but I'm not sure just how much. Then I dump Sevin dust on all their dusting spots in the yard (if it isn't raining).
Hope this helps. Wild birds, mice and other critters will reintroduce parasites that will reinfest your barn and your birds eventually. For now, I think this is the best I can do at my place.