Oh man, I always get that mixed up! I think you mean "sherd," like a piece of broken pottery. Found a killer one last year that had this glossy, almost metallic blue glaze on it. It was just a tiny triangle, but you could tell it was from something fancy. Made me wonder about the whole pot it came from.

Yeah @karencampbell, I just give mine a quick damp wipe first.

Yeah, laura_chen41's cloud backup tip saved me too!

Yeah but a meter can show a locked rotor too.

Wait, is the goal here to make pie or start a cleaning supply company? A full cup of vinegar sounds like you're trying to pickle the flour. I've heard of a spoonful to stop gluten from forming, but that much acid would just make a weird, tough mess. Some of these "secret tricks" are just people mixing up their measurements.