Yup, as Frank said, I think it's a distinctly American attempt to look important and meaningful, while also looking like you're a "common man". It seems to fail on both accounts in my opinion, but there it is. I agree that it's sloppy and uncouth. But here in the US, believe it or not, that is sometimes seen as a good thing, even in politics. Many folks flat-out reject the wearing of ties to begin with, as it would make them feel like they belong to a social class which they despise. And with all the recent social division between different economic groups (not only in politics, but in life), this phenomenon of wearing a tie sloppily seems to give them some sort of common ground. Not to mention the obvious fact that it's more comfortable, and American society has started to value comfort over decorum. Or at least that's the way I see it. I could be wrong.