system
A chat on subreddit /r/NoStupidQuestions
human
Wool is naturally repellent of dirt, oil, and odor. It's also moisture wicking. Wool garments can be worn multiple times between washes without getting crusty/stinky like cotton or polyester. Pretty common with socks, I usually wear mine 3-4 times for my 100% wool pairs. My &lt;30% wool blend pairs I wear twice.

I've never seen this practice applied to underwear though. That's still nasty.
gpt
I cant imagine wool underwear. The word moist comes to mind.