If the hanky is clean, then it's been washed and laundered and there's no way to prove whose it was.
But if it ISN'T clean, then presumably it contains bodily excretions of some sort (sweat, snot, whatever) - which means that what's
really
for sale here is a sportsperson's DNA.
What could possibly go wrong?
~~~~ Just another victim of the ambient morality ~~~~
I never heard of him either. Even if I did, I wouldn't buy anyone's used hanky for any reason.
If I took a hanky, wiped the sweat from my brow with it. Blew my sinus filled nose in it, then drew a deep breath and hacked into it, then handed it over to you...for free...would you take it and cherish it forever and ever? Probably not.
For all you know my username is Shyleagh and I play RuneScape. But what's behind a name? Maybe I'm a famous rapper, someone who works for a government someplace in the world, an inventor who invented something that has been a game changer or maybe a life changer or perhaps a world changer. I could be a Scientist who is working on a complete cure for COVID-19. I could be your teacher, the CEO of a company that is very well known globally. Why not take my used hanky? I'm probably more important that that Messi guy or gal.