In Korea, why are the feet so black and smelly? The biggest contrast is the top of the foot and the sole.

They’ve been in these shoes all day and they need a proper cleaning. I really didn't intentionally dirty these precious feet. It's just from sweating all day walking around in boots. Korea has a lot of mountains. These feet weren't staged.
They walked all day in boots. Sweat, heat, and whatever the mountains put on them.
Pure natural dirty feet.
You know what you’re supposed to do.