That Snot my Rag

I just put on my sweatpants (aka my house pants) and found a used handkerchief in each pocket. How does one decide when a handkerchief is dirty? After one day? after that one serious nose blow that leaves you feel like you're folding up a half-baked orange marmelade fruit roll up...one made with the chunky bitter marbelade with real pieces of orange peel... or is there some other way to know when your nose has had enough? when the cotton has adsorbed enough of your nasal stuff? for my friends with kids, this question probably ranks as pretty low interest on the body-meets-clothes/textiles meter. but now that i'm okay with wearing socks two days in a row, I need something else to think about in this regard. btw, are we the last house on the block using handkerchiefs?