1969 D LMC Floating Roof

Well it seems there is evidence of the post on the left side so not a true floating roof coin. And during polishing the FG initials do become worn (like yours) or gone also.
So really no need to worry about the black spots as the cent is just a spender. BUT, if you want to try to work on the black spots you can try a soak in pure (100%) acetone ($) then buy a $15.00 bottle of Verdi-care and try that also. (Much cheaper to just spend it though )

EDIT: Or just keep as is untill you find a better example.

agreed not a floating roof.