Smiling boosts your mood and makes you look more attractive, and some stars use that to their advantage to grin their way down the red carpet. Others seem to prefer the aloof look and barely crack a smile. Why are so many of our biggest stars so brooding in public? For some, it’s part of their well-crafted persona. Others take the opposite approach and can’t stop grinning. Here’s a look at Hollywood’s crabs and hams.