I'm not a doc but I would argue that the guy must have had severe fungal infection of his feet to get to a point where sniffing his socks poses a health hazard. Maybe even immuno-compromised. I doubt you can contract this from healthy feet even if you sniff them daily :)

People regularly underestimate the damage of breathing in mold and fungus spores.

>I have no idea why, though.

You mean, besides them being awesome?

This answer is great, because it’s just something people like. Some people like espresso, some people listen to hip hop to relax, some people find meaning in Jackson Pollack paintings. There may be some underlying cause for foot fetishism like there is for the taste of cilantro. But ultimately, what’s awesome to you?

> I have no idea why, though.

Check out the "The Penfield homunculus" and note that in the brain's sensory map, where we process foot sensations is very close to genitalia.

Sure, but how is this relevant though?

It's other people's feet people like, not their own (and so don't themselves feel those sensations when they touch them or whatever).