in my opinion, Michael always had this cool look that comes from his facial gestures and the shape of his face.. So no matter how he aged, if he was thin or a litttle thicker, or done anything to his face the true essence of coolness always stayed.. With This Is It he brought the coolness as usual.. Something about his face always stayed with him but he did look extra thin and what I would consider unhealthy even though he met health standards..
Michaels face always shined, he never lost that spark in the eye, and how his nose and mouth would crickle in sertain ways when making facial gesturs always brought that"i'm confident, cool, and im the shit" feel that was freaking awesome.. that's why when anyone copies Michael they gotta do the faces.. its just the coolest lol