Oh man, that's the worst. I once spent a whole day just trying to explain why you can't use cardboard as a vapor barrier, lmao. With the ceiling, I'd just show them a picture of the sag and the thin drywall next to a tape measure. Tell them the old work was basically held up by hope and a prayer, and you're fixing it so it doesn't fall on their head while they sleep. If they still complain, maybe offer to put the old soggy piece back up and let gravity do the talking.

Got the Bosch. How long have you had yours? Any problems with it yet?

Yo, the real game-changer for me was how much less my wrist hurts now. Staring at the screen where my hand is instead of looking up at a monitor actually fixed my posture without me trying.

Try cleaning it with baking soda.