I'm not sure when I first noticed it. But President Obama does say it often. Still his tone is so very different than most of the current crop of candidates. And I use the term candidates loosely.
"Look, these politicos are the most immature, insecure, inept group in a good while." Why the quotation marks? That's the point. Have you ever noticed how many times that politicians respond with a sentence that begins with "Look" or "Listen?" I have. Seems like this is a fairly recent occurrence. I submit that it is fairly significant as well.
It's the attitude of using this imperative one-word sentence that bugs me. Not only is it school yard rhetoric, it's definitely the language of power. It's a commandment for you to stop what your doing and see things my way.
If you were ever in an English class that went deep with parts of speech and types of sentences, you might remember the classic one word sentences that were usually exclamatory. Stop! Don't! Look! and Listen! Remember how these were diagramed? (You) / Look! It's commanding you to do something, not that there is always something wrong with that. But the way politicians avoid a direct answer to a question, it gives them a leg up on districting their response while seemingly authoritative. Just my view, but see if you don't feel a bit put off when instead of giving you something specific in the way of a courteous response, someone tells you, no commands that you look! As if you need to see something. Now in the case of an oncoming car or any other physical threat, I will definitely look.
And while we're on the subject of sentence structure, this is as good a place as any to reveal and share the all time sentence diagram stumper of my days in high school Language Arts classes. Mr. Carpenter, my 11th grade teacher gave us this sentence to diagram: The Private laid out his bedroll over the Sergeant's objection. Look, it was a real challenge to place that prepositional phrase beginning with over somewhere.