I always liked how his Win animation in Halloween is him getting a fistful of chemicals and turning invisible. Reminds me of the original The Invisible Man.
Guess the Smile we see is a zombie or some other animate corpse. Blue skin, at the end of the book Griffin gradually becomes corporeal as he dies and in Smile's interview he admits his bandages/clothes/makeup aren't a good cover-up when he does his thing ...which implies again he's not transparent underneath all that in the first place. The disembodied gloves in some promotional art could mean he just put them on after.