Started tightening the chuck on my drill press one time and the key slipped, sent me into a whole spiral about calibration on everything in my life. Checked my bathroom scale against a bag of flour, my oven temp with a separate probe, even my tape measure against a ruler I trust. Now I keep a little notebook with dates and readings for everything, which drives my wife nuts because she just wants coffee without a science project attached. But honestly, cheap gear drifting that far feels more like a factory defect than normal wear, 30 degrees off is wild. Your kettle trick is smart though, I do the same thing now before every new bag of beans, takes two minutes and saves a lot of sadness.

Sounds like bragging, doubt a weekend course is the whole story here.

That "can save you from costly repairs down the road" line is pure smoke. I had a guy try the same thing on a used F-150 last year, and when I asked what the deductible was on a single paint chip repair, he literally flipped through the brochure and couldn't find it. I told him to take it off or I'm walking, and suddenly he found the "no cancellation fee" button real fast. The trick is to sign nothing until you've read every line, and if they start with the pressure talk about "this is standard on all our deals," that's your cue to stand up. Also, check your state's lemon law or consumer protection page, most of these add-ons have a written 30 day out clause they never mention.