• I kind of write about this in my book: smilers versus non-smilers. I'm convinced we all fall into one of these two categories.

    Smilers are liked. Non-smilers are not liked.

    We cozy up to smilers. We avoid non-smilers.

    Which might explain why a lot of us don't much flip over Muqtada al-Sadr. Not only does this cleric not smile. He scowls, which is even worse than not smiling.

    He's right up there on the nasty charts with Usama bin Laden, who doesn't smile either. Both men have their followers, but it's got to be fear. They aren't scoring points on the warm and fuzzy front.

    I suspect John Kerry has problems smiling, though when he does, he does loosen up a lot. He should take a cue from Al Gore, who in his debates with George Bush, never smiled, but did sulk and hiss. I think it cost Al.

    President Bush is a smiler. Although he should probably be careful, because his smiling sometimes becomes a smirk and the Washington press corps hates smirks -- which might be why he's smirking in the first place.

    I think his predecessor Bill Clinton got out of a whole heap of trouble because he was a great smiler -- maybe a bit too smooth for some. But he dodged a lot of bullets with that smoothery.

    John Kennedy? Smiler. Richard Nixon? Non-smiler.

    Winston Churchill? Smiler. Adolph Hitler? Non-smiler.

    You get the point. Smile and the world's your oyster. Scowl and you're an oyster… without a pearl in sight!

    Watch Neil Cavuto's Common Sense weekdays at 4 p.m. ET on "Your World with Cavuto."