OK, I understand now.
Open mouth just enough to convey he's up to something, probably up to no good. But not open mouth to convey he is laughing or is joyous.
In that case I would agree, afterall, he's suppose to be a mischievous character.
Exactly. The problem with the Cannibal and DX heads is they sculpt the left side of his mouth such that he looks like he's smiling. Jack smirks, and it most of the lip expression should be kept to just one side to look right.
I think EB may have even used that photo as reference for their sculpt. I'm eager to see more photos of it to see if it's truly lighting or their sculpt that's causing the evil qualities in their preview shot.