Mmm. This one may rile up some contention.
Ponytails and long hair.
I've never received a straight answer from nerd types why they keep long hair. Yet, it isn't only that the hair is long out of preference, but it's long and often times unkept due to laziness. Time to let go, my friends. Visit a local barber and ask for an updated, neat style which will compliment your features. And don't fret, you can always buy a wig for your cosplay outfits.
As for the thinning or receding hair type, there's no use hiding it, and the public can not be fooled, I promise. Shave it low, or man up and shave it off.