One of the things about watching cable television – that is, actually focusing on it, studying it, rerunning the online clips – is how stupid the people on it can seem.

This is undoubtedly because most people on television are not all that smart (and why should they be?). And because when you have to talk for the sake of talking – which is the job at hand – your blather quotient is going to increase. And, too, because no matter how much practice you have at blathering and how much boilerplate you can regurgitate, unscripted moments can be as rough on cable heads as on politicians.

But, perhaps most of all, you get revealed when your talking points are weak.

Tucker Carlson, who has been retailing a 2007 video of an Obama speech about post-Katrina reconstruction, is a pleasant, charming, often humorous, B-level political commentator. He has managed to become modestly well-known without quite succeeding at any job he's held. After unsuccessful tries at print journalism, and after being bumped as a conservative commentator from MSNBC and CNN, he now has a conservative website.

His shocked-shocked curation of the 2007 video most generously comes under the heading of "it's hard to make a living". The principal charge here is that Obama seems to suggest that the delays in reconstruction after Katrina might have something to do with the fact that so many of the people in New Orleans are poor, powerless, underrepresented, and, as it happens, black.

Carlson's view, which has been echoed now by Drudge, and much of the Fox line-up, is that this dangerously, insidiously, and rudely sets black Americans against white Americans. According to Fox, critics are saying these "are racially charged remarks that promote class warfare". Pay no attention to the fact that the critics are primarily Fox itself.

But that is not the notable part. The notable part is how poorly, and sheepishly, just this side of red-faced, the Fox commentators are making this case.

Carlson's interlocutor on the morning show Fox & Friends, Steve Doocy – not, in any situation, television's brightest bulb – can hardly manage a coherent sentence ("municipality, or state, or local government, or something like that", he says, focusing on the issue of relief administration). He goes from notes, to prompter, to listening to the producer in his ear, in an effort to somehow figure out just exactly what the issue is here – and, hoping against hope, not to be humiliated by it.

Carlson himself, with freshly-dyed hair, seems just to smirk and look sidewise, while he accuses the then senator of, five years ago, "whipping up fear and paranoia".

Indeed, the outrage and umbrage – most of all, it seems, about Obama "cadence" – deflates as it is uttered.

In a remarkably short cycle, it was Fox itself that, having primed this bombshell, then defused it. Fox's Sean Hannity acted as straw man and allowed himself to be demolished by Fox's Juan Williams, the network's designated defender of the president. Similarly, Greta Van Susteren had the Tea Party Congressman Allen West pooh-poohing the whole affair.

In part, this is a concise demonstration of the Fox method: not just a toxic polemic, but one that they carefully test and calibrate. In this instance, floating it out there and then pulling it back in, with some reflexive grumbling about liberal bias.

And, in part, it is a measure of the franticness at this point in the campaign and of how little the Republicans have to work with. On the other hand, why not try it?

The only downside is that everybody looks even stupider than usual. But there is no real cost in that.