This one actually was cleaned with just some soap and water because when I found it,it had been almost fully covered by someone with some sort of hard substance that was black and green covering entire back of coin and from nose down on front of the poor coin. Took me quite some time to break it all off and keeping damage minimal as I could. I dont know what they had dumped on it but I'm glad I took the chance to save it. Some people are ridiculous.
But consequently it had to be cleaned to get all the small leftover pieces off fully and not scraping them off.