My $12 moisture meter saved my drywall from a moldy end
I was patching a wall in my basement after a leak and kept slapping on mud over what I thought was dry surface. After two coats bubbled up overnight, I grabbed a cheap pin moisture meter from the hardware store and scanned the whole area. The reading near the floor joist was 18%, way above the safe 12% or less for paint, so I cut out a 2 foot square and found the sill plate soaked underneath. That little gadget paid for itself in one afternoon, and now I check every spot before I even think about texture. Anybody else trust their eyes over a meter and regret it?
Honestly, I read a study once that said most mold issues in basements start because people skip checking moisture behind walls, so you're way ahead of the game. Tbh, I've been burned trusting the "looks dry" test, and that meter saved me from a way bigger headache.