Virginia Postrel:

Candid shots are particularly perilous for people with animated faces, who illustrate their speech with bulging eyes or distorted mouths. In person, they look lively and entertaining. But, in between more flattering expressions, they produce a lot of strange shots. That’s why Hillary Clinton’s enemies have no trouble finding silly photos of her, while Barack Obama’s foes must make do with shots in which the candidate isn’t gazing glamorously upward. Obama’s cool countenance makes weird candid shots less common.