A TPG designating "environmental damage" on a coin happens. You'd want to search auction archives on Heritage and just look and look until you locate and see enough examples. High Res imagery on that sight is second-to-none and you can get a heckuva education if you put the time in.
Here is a coin that could have gone either way when I picked it up raw for only $80 on ebay. Instead, PCGS found in its favor and gave it an EF40.



Here is a coin that could have gone either way when I picked it up raw for only $80 on ebay. Instead, PCGS found in its favor and gave it an EF40.
























