I've noticed there's a thing where our brains filter out fine details, especially in mirrors. When I have a lot of time to pluck and want to try to get everything, you can sway left-right in the mirror to try to add a kind of dither, visually, and that helps see stuff you wouldn't, otherwise. However, knowing this is terrifying because then you start seeing all kinds of stuff that other people probably see that you normally don't and now I wanna die. So, use this knowledge with caution.

That's my theory for old people with sudden face hair. Not that it grows, but it's hard to see.