Thank you for sharing these superb insights. I want to add my “ditto” here.
My microbiologist thought partner explained to me that after we spray our “disinfectant” liquids and they dry, many such commercial products leave a residue of organic compounds behind. It will be in a visible “crust” unless removed by (sterile) water or (sterile) alcohol – or better yet – sterile water allowed to thoroughly dry, followed by sterile alcohol allowed to thoroughly dry. He explained that the residual of disinfectants can be thought of as “germ food.”
You are correct in saying that we should never intentionally spray anything toward the delicate wonder that is our HEPA filter. Microbes of all variety and stages are ready to spring to life as soon as they are presented with the right conditions of oxygen, water (they’re microscopic by definition, so humidity matters), and organic nutrients. That’s why we call them, “germs.”
The every action and activity of every qualified operator relative to our equipment and environment should reflect this awareness. Training is absolutely key and must be universal and comprehensive.