Almost nothing is more pointless — or popular among journalists — than seeking to diagnose the public mood based on TV or movie preferences. Such stories allow political and cultural pundits to stray outside their customary confines, positing what “Avatar’s” success, say, augurs for environmental policy.

For the most part, such exercises amount to empty calories. However, recurring themes among the programs that get on do at least say something about what executives and producers perceive as apt to strike a nerve with sizable audiences — and can thus become interesting when certain leitmotifs start appearing in multiples of two and three.

Right now, there are a couple of mini-entertainment trends that each speak to aspects of the polarized political climate in the U.S.: The first, which is struggling ratings-wise, involves paranoid concern about aliens walking among us who mean to do us harm. The second touches on the economic divide and heart-warming benevolence of the elites, at a moment when the debate over tax cuts has triggered discussion of class distinctions in a country that generally doesn’t much like acknowledging them.

The shared theme here, such as it is, has to do with not judging books by their covers — with the millionaires and aliens both hiding in plain sight. Though on one side, that’s because goodness and charity awaits us, and on the other, mass annihilation.

Although both strands seem to originate from a conservative foundation, the notion that otherwise ordinary-looking people are inhuman invaders taps into fear and uncertainty, while the “millionaires are just big ol’ teddy bears” concept largely seeks to reassure. In that second case, we even have a bit of a ratings baseline to consider, since “Secret Millionaire” — the ABC reality show that recently premiered to nearly 13 million viewers — drew a much smaller audience two years ago in an earlier run on Fox.

Both “Secret Millionaire” and CBS’ “Undercover Boss,” which has also been quite successful, employ a similar conceit.

In each case, someone wealthy and privileged (a self-made millionaire and company CEO, respectively) wants nothing more than to share personal wealth or rewards with those who are less fortunate. Far from the slick fatcats who nearly toppled the financial markets, those in the highest tax bracket have the kindly ways of a reformed Ebenezer Scrooge on Christmas morning.

By that measure, these programs tap into an idealistic image of America, where amassing wealth is less important than sharing it. Nor are there many trust-fund babies among the participants, reinforcing that you, too, can make it if you try.

A darker conservative view resides in the current strain of science-fiction dramas where aliens aren’t just coming, but are, in fact, already here — having infiltrated society, the better to orchestrate its demise.

These series and a spate of upcoming movies — including ABC’s “V” revival and NBC’s just-returned “The Event” — all seem culled in part from the darker recesses of a post-Sept. 11 psyche. And these infiltrators are only slightly more insidious than the invaders in the movie “Battle: Los Angeles” and upcoming TNT series “Falling Skies,” which, like “The War of the Worlds,” shoot first without bothering to ask questions later.

Such entertainment can be seen as elaborate therapy — a fanciful way of working through deep-seated anxieties, just as the Cold War era produced lots of TV shows and movies about daring spies seeking to outsmart evil foreign operatives with bad accents.

Interestingly, both “V” and “The Event” opened reasonably well, then saw their ratings quickly drift downward. By happenstance, the narratives in the two shows have also converged.

So can we infer any larger lessons from either of these trends? Probably not — just as it’s hard to connect the dots regarding fear-mongering Fox News host Glenn Beck’s shrinking audience, which hasn’t stopped any number of analysts from trying.

On the one hand, it’s comforting to think entertainment choices really can convey something about collective hopes and fears, allowing us to make more sense out of the numbing patchwork of images and ideas we absorb daily.

The reality, alas, is more complex than that. And other than the perception that consumers of entertainment like being surprised — whether by aliens wrapped in human skin or CEOs slumming in overalls — audiences seldom disgorge what truly motivates them quite so easily.