A lot of golfers take the club back with almost no upper-body rotation - they're all arms. And even when they do rotate back, it's usually on a flat shoulder plane. If your shoulders turn back fairly level with the ground, it's hard to swing down from inside the target line and hit an accurate shot.
I'm not always smiling when I'm on the golf course. Sometimes, hey, listen, people have regular jobs. You go to them when they're working, and you catch them not in the best moment either. So I understand how people could perceive me. But come get to know me, and I'm totally a different person.