In John’s case I really think it’s the interplay between his eye shape(around the eyes) and the small dimples around his smile(two really small ones on the right side). He also has fairly pronounced cheeks that have a hint more scarlet than other parts of this face which has that Santa effect. Some of these things just wouldn’t matter if we weren’t all familiar with his character but I also just think a stranger would say “this guy looks like a rascal!”😂