This Tuesday morning I was getting dressed, and I saw an odd looking coin on the floor of my bedroom. So I picked it up and looked it over, at first I thought it was just an ugly dirty dime. Then I noticed how the toning looked exactly like copper. As I studied it a bit closer I was pleased to find that it is in fact the copper which should have been under the cladding. Now my ugly duckling of a dime became a beautiful swan of sorts. I know it's really only worth a few dollars but that's thirty to fifity times the face value of the sorry looking dime I thought I found. Sorry about the reflection though the "rty" in Liberty, but I put it into a 2x2 holder prior to photographing it.
I don't think it's improper cledding, just someone tried plating it and got bored. I have tried it on a dime and it turns out like that.
I dunno. How are the raised (and worn) areas - FDR's hair, cheek, chin, nose, eyebrow as well as the lettering - clad but the lower areas are not. In other words, if half the planchet was not clad and then it was struck wouldn't ALL of that portion of the coin be unclad? How then did the higher portions of the devices and lettering become clad and the other area not? I think your coin is stained. I think it was stained and the stain at the higher areas noted wore off in circulation. (But I could be wrong.)