WD40 then degrease it with Alcohol, but as someone already mentioned, Alcohol can sometimes work pretty good by itself. I discovered by accident that hand sanitizing lotion, the ones made mostly of alcohol, works very well to remove sticky glue residue, and I suspect some other types of transfer marring or smudges, as long as it isn't too old. You will then have to degrease the area though, becuase those hand sanitizers sometimes have moisturizers in them.

Chombi