Putting a pan of grease in someone's bed is a bold move, but after 9 days I can't say I blame you. A normal conversation only works when the other person is actually listening, and Dave clearly wasn't. Sometimes the message has to be a little weird to get through.

People keep acting like a random barista is some kind of coffee oracle but half the time they're just guessing based on what works for their own shop. Two clicks on a hand grinder is basically nothing, that could just be burr wobble finally settling in or your beans aging a day or two. Also a cup that tastes like burnt tires usually means over extracted, which means too fine, so going coarser makes sense, but you could've figured that out a year ago by just tasting and adjusting one variable at a time. The stranger didn't fix your coffee, you did, you just needed someone to give you permission to change something you'd already decided was right. That $40 grinder thing bugs me too, price has nothing to do with it, a cheap grinder can still be set wrong. Learn to taste a sour cup vs a bitter cup and you'll never need a Portland barista to tell you anything again.