400F dries them out at 18 minutes. Go 375 and flip once.

Man, that would mess with my head too. I've had somebody swear up and down they checked something and it turned out they didn't, and it's hard to shake that feeling after. Good on you for trusting your gut and surfacing when something felt off.

Had the same thing happen with my washing machine drain hose a couple years back. Water kept backing up and the whole laundry room smelled like a swamp and I was ready to call a plumber. Turns out the hose had a little kink in it and the check valve thing was stuck open so nasty water just sat there. What fixed it for me was pulling the hose out, straightening it, and running a bucket of hot water with dish soap through it to flush the gunk out. I also started checking that flap valve every few months now because once it flips or gets gummed up it's the same problem all over again. The real lesson is to check the cheap stuff first before buying tools or dumping chemicals down there. Those drain snakes are handy but they won't do a thing if the problem is a flipped seal letting water sit.