To begin with, journalists exposing the mayhem of the Trump administration sounded a shrill alarm: the incendiary slogan of Michael Wolff’s book was Fire and Fury, after which Bob Woodward’s Fear disseminated creepy dread. Since then, the mood has changed. Philip Rucker and Carol Leonnig, reporters for the Washington Post, remain aghast, but they also respond to Trump’s manic or even maniacal behaviour with a kind of nihilistic glee. As we hurtle through the daily crises he incites, can’t we at least enjoy the ride?

At one point in A Very Stable Genius, the conservative lawyer George Conway – the husband of Trump’s acid-tongued apologist Kellyanne Conway – doubles over in incredulous mirth at the man’s idiocy. Then the joke palls, as Conway realises with a shudder that “the object of his ridicule was the president of the United States”. We’re lucky that it’s only Trump’s hissy fits that are “thermonuclear”; instead of launching missiles, he childishly makes war by weaponising sweets. At a summit he tosses two Starburst candies at Angela Merkel and grunts: “Don’t say I never give you anything.” I wonder what flavour he chose for this undiplomatic exchange: sour or summer blast?

Although the title of A Very Stable Genius ironically adopts Trump’s preening self-description, Rucker and Leonnig present him as a lord of misrule who delights in instability, running a government that resembles “a virtual tilt-a-whirl” at a carnival. Despite his claim to be a genius, under his combed-over crown he has an entirely vacuous head: he tells India’s prime minister, Narendra Modi, that it’s a good thing the country doesn’t have a border with China, and at a ceremony in Pearl Harbor he asks what exactly happened there to justify the commemoration. Forget about CIA briefings: as Steve Bannon puts it, Trump “doesn’t even know what intelligence is”. As proof, Rucker and Leonnig have a scoop about one of his crazier wheezes. Denied funds for his wall along the Mexican border, he proposes a human chain of hefty enforcers, hundreds of thousands of them, who would join hands in a barricade extending across 1,200 miles. A stable genius or a rampaging dimwit?

Donald and Melania Trump exit the pitch before a college football play-off game between Clemson and Louisiana State, January 2020. Photograph: Matthew Emmons/USA Today Sports

In the more decorous 1970s, expletives were deleted from the transcripts of Nixon’s Watergate tapes; such coyness would erase most of the confidential dialogue Rucker and Leonnig have reconstructed. “Oh, fuck’ is the refrain of John Kelly, a chief of staff driven to distraction by the whims of his boss. When Trump cravenly crumples during a talk with the bellicose Turkish president, an admiral in the defence department lets off pressure by exhaling: “Phhhhfffft”, then manages to utter: “Fuck” in agonised dismay. Portly Mike Pompeo, now bustling around the world as secretary of state, has to be metaphorically “fluffed up” for a job interview with Trump: don’t ask me how I know, but fluffing is an oral service supplied to porn performers to ensure that their erections are primed.

Bodily emissions abound, both liquid and solid. Trump is regularly “pissed”, and Nancy Pelosi describes one of their tiffs as “a tinkle contest with a skunk”. Trump’s gruff crony Chris Christie warns of a “shit storm” when James Comey is fired; after Christie refuses an offer to replace Kelly, Jim Mattis, then on his way out as defence secretary, congratulates him for escaping “the shitshow”. About to inform Trump about the lies that got Michael Flynn indicted, FBI operatives prepare to “drop this turd on him”. As the poop exponentiated, I imagined the White House smeared with ordure. No wonder John Bolton, said to be “anal retentive”, didn’t stick around for long.

If Trump is a lax, dribbling sphincter, then his stony-visaged wife Melania might be called a sphinx, silently guarding her secrets behind outsize dark glasses. In Free, Melania the “lifestyle journalist” Kate Bennett does little to demystify her, but she cleverly analyses her politicised dress sense. Melania relies on her spiked heels to belittle Karen Pence, the squat, sanctimonious wife of the vice-president, and she occasionally wears trousers to antagonise her husband, who thinks that female legs should be permanently bared. The camouflage-green Zara parka she wore on a supposed mission of mercy to a shelter for unaccompanied children in Texas propounded her creed: on the back, in a nonchalantly cynical shrug, it said: “I really don’t care. Do u?”

Melania, Bennett reports, values the “privilege and prestige” offered by Trump, and can do without affection. The hollowness of the arrangement was advertised by their wedding cake, which stood seven tiers tall, with internal wiring as intricate as a Trump skyscraper, but turned out to be inedible, because to ensure that the facade stayed upright the confectioners had to leave the gooey filling out.

It’s not surprising: falsity, fraud and infidelity are the hallmarks of Trump’s brand, and in A Very Stable Genius he admits as much, with a sneer of contempt for the fools he hoodwinks. “I’m a total act,” he tells Anthony Scaramucci, “and I don’t understand why people don’t get it.” Like his boast about being able to shoot someone on Fifth Avenue with impunity, this is an icy, Iago-like glimpse of the emotional and moral nullity that may be the source of his power. On reflection, Rucker and Leonnig’s book needs a different, less brittly ironic title: they should have called it Evil Genius.

• A Very Stable Genius: Donald J Trump’s Testing of America by Philip Rucker and Carol Leonnig is published by Bloomsbury (£20). To order a copy go to guardianbookshop.com. Free UK p&p over £15

• Free, Melania: The Unauthorized Biography by Kate Bennett is published by Flatiron Books (£27.99). To order a copy go to guardianbookshop.com. Free UK p&p over £15