Looks like he was Slimy even BEFORE he was an apparition! Portrait of Slimer (Ghostbusters) as a human. *EDIT* Per request, a close-up... And him in the movie just so you can see what he looks like as a ghost...
I updated this goober with my more recent signature for an upcoming Ghostbusters Art show called "Ectoplasmic Residue." The show premieres tonight at 5pm at Cine Athens - 234 W. Hancock Ave, Athens, GA.