> Occasionally a reviewer will spot a bug. Occasionally there will be a false positive that turns out not to be a bug.

And most often of all, while explaining what they've done, the reviewee will say "and this does... oh crap, wait" and fix the mistake themselves. Among all their other virtues, a code reviewer is a level 2 debugging duck. (Although all of my code review experience is with buddy check-in style reviewing rather than sending it off to be reviewed. I can understand endless nitpicky questioning being annoying if you're doing it offline.)