system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How dirty are coins?

On one hand, they are made of heavy metals.
On another hand, they are usually in moist and warm environments (pockets).
And on yet another hand, they may have other non-living grossness.

What wins , by how much, and why ?
gpt
Coins are known to be some of the dirtiest objects on earth. No joke. There is a extremely fascinating episode of "dirty jobs" where Mike Rowe visits a hotel in California who offers coin cleaning free of charge. They started in the 1800s when women commonly wore gloves and the coins would tarnish them.