Why are good things seen as bad, and why are bad things seen as good?

Greg Gutfeld poses the question and supplies an answer in “Not Cool: The Hipster Elite and Their War On You” (Crown Forum). Gutfeld paints a picture of a coolocracy in which the world is run by star-bellied Sneetches who tell us what’s hip and we obediently keep running in and out of the belly-star-making gizmo.

Icons of cool like Robert Redford, Mark Zuckerberg, Jesse James and Yoko Ono get shredded in the book, which is as breezy, enlightening and funny as Gutfeld’s two TV shows, “The Five” and “Red Eye.”

On both shows, the way he delivers truths disguised as jokes makes him a kind of reverse Jon Stewart.

Gutfeld finds that cool warps everything. In 2012, for instance, Zuckerberg’s Facebook not only didn’t pay any net federal income tax but was actually due a refund of about $430 million. Why? Because the company (lawfully) deducted the stock options it issues to Facebook employees, many of them now deliriously wealthy because of those options. If Exxon or Koch Industries had managed that, someone might have noticed.

But because it was Facebook — a company that oozes cool out its pores — it was a one-day story that people forgot about. “If this company were something that actually made something in a factory or a field,” writes Gutfeld, “it would be roundly condemned by every single media hack on the planet.”

Never mind that companies like Exxon and Koch supply the energy without which Facebook wouldn’t work: They’re not cool.

Hipster iconoclasm dates back at least to the 1950s (James Dean, Marlon Brando), but cool remained outside the establishment until the Woodstock Generation began to take over. It imposed warped values — artfully cultivated rebellion, counterproductive liberal “social consciousness,” romantic outlaw status for murderous enemies of America (the Weather Underground, Mumia Abu-Jamal, the Boston Marathon bombers) — on the mainstream. Today Flower Power types run the media, the networks, the Hollywood studios, even the Justice Department.

But ask someone in their 80s and 90s what’s cool, Gutfeld figures, and they’d probably say something like, “Killing Nazis.”

A 1950s study that tried to measure coolness of jobs identified five factors that gave a career prestige: importance of the task performed, level of authority you have, the know-how required, the dignity of the tasks required and pay.

Scoring highest were jobs like bankers, executives, ministers and professors.

Fast-forward to today, when, writes Gutfeld, “the Labor Department reports that only 47% of Americans have a full-time job. That’s because it’s hard to get full-time work as a maker of artisanal tricycles.” “Raising awareness” didn’t strike anyone as much of a career in the 1950s, but a recent survey of 350 college students discovered that “social consciousness,” i.e., daft activities like collecting signatures on petitions for Greenpeace, was among the accepted cool traits.

The end result of eco-minded hipster thinking is, for example, the San Francisco ban on plastic shopping bags. This well-intentioned move in favor of all that is green and natural actually wound up killing people. Why? Because when you use bags to transport food, bacteria collects in them.

Reusing that Earth-friendly tote gradually turns it into a chemical weapon. The ban, declared a University of Pennsylvania study, “is associated with a 46% increase in death from food-borne illnesses. That implies an increase of 5.5 annual deaths for the county.” (The researchers added that this was a conservative estimate.)

So the bag ban is basically a serial killer on the loose. But it’s cool because we probably saved the lives of at least five seagulls, and more important, it makes us feel cool. More cities are sure to follow. A similar jihad against DDT, which saved an estimated 500 million lives, according to The Economist, has led to the deaths of perhaps millions in Africa, where cool environmentalism meets cold, hard reality. Now a few groovy artisanal types are sounding the alarm about vaccines, with predictably depressing results.

A year ago, a Florida county saw its first death from whooping cough in decades. The victim, a baby, had parents who decided not to vaccinate.

Vaccines, DDT, genetically modified foods — all these things are unnatural or impure, hence suspect.

“Purity is a big thing with the coolerati,” notes Gutfeld. “But, like cool, it exists separate from the notions of good and evil. Pure sugar is delicious. How about pure cocaine? How about pure horses–t?” That depends: Is it locally sourced?

OK, so why aren’t conservatives cool? Gutfeld makes a valid point: “From my experience being around conservatives, it’s extremely frustrating how dismissive they are of ‘weird’ things, and that hurts them.”

Gutfeld chooses the music that backs his segments on “The Five” and “my choices are never met with ‘That’s good’ or ‘That sucks.’ It’s always rewarded with anguished looks on the other panelists’ faces and the two-word review, ‘That’s weird.’ ”

Automatically dismissing tradition and latching onto whatever’s new isn’t cool. But neither is being closed-minded.