Say what you like about the biographer Tom Bower, he hits the ground running: from the opening bars of House of Beckham, an epic symphony of snide, you know exactly where you’re going and how you’re going to get there. So, it’s Glastonbury 2017, and Beckham is “in deep conversation with Mary Charteris, a 30-year-old married party girl, the ultimate cool Sloane Raver”. She is, we learn, famous for “being present at parties where others enjoyed cocaine”. Is she meant to be a cokehead by association? Can one catch cocaine? How do you get famous for that?

It doesn’t feel especially fair-minded, but the more blameless victim in this take-no-prisoners prose style is syntax. After Charteris’s wedding in 2012, “everyone latched on to her father’s excited reaction to the unusually revealing dress she wore and on to her stepmother known as ‘Lady Mindbender’”. What does it mean? Excited how? Who’s everyone? Latched on to the stepmother in what way? In the end, trying to tell a story with no better sources than contemporaneous tabloid accounts, skating the same line between insinuation and defamation, while trying to introduce notes of both moral and factual authority, well, it can be done, but only if you’re happy to sometimes not make sense.

Back in Glastonbury, Beckham and Brooklyn, his eldest son, are later witnessed in the same establishment as people who “were seen taking ecstasy”; neither Beckham partook, Bower plainly states, though how would he know that, and while we’re here, how can you see a person taking ecstasy? It could have been a Piriteze.

Anyway, reader, I think we’re meant to conclude that Beckham and Charteris were up to no good, as he “appeared to be smitten” by her, but “also attracted the attention of a glamorous Australian bikini model”. Where does “smitten” sit, on the infidelity-o-meter? Is it, strictly speaking, his fault, if he attracted a woman’s attention? You want an ancient judge to intervene, peering over his half-moon spectacles, to ask: what, exactly, is the allegation here? That David Beckham stood next to a woman, who has stood next to cocaine, a further woman stood close by, and nobody knows what happened, but it must have been bad, because otherwise why would Victoria have looked angry? Allegedly.

There are much smokier guns in the book, as regards David Beckham’s infidelity, detailed accounts of his text message and travel history with Sarah Marbeck, Celina Laurie, Rebecca Loos, Danielle Heath. All of this is quite historical – the annus horribilis from the institution of marriage’s point of view would be 2004 or, to put that another way, 20 years ago. Perhaps more problematic for the biographer is that it was all already in the public domain, courtesy of many overlapping newspaper reports and in quite granular detail. So without anything from inside the house of Beckham, and almost nothing new from the many women involved, Bower’s is more of an aggregator role. Chat GPT could have done the whole thing faster, with the prompts: David Beckham – erection – sun lounger.

There is one fresh detail about Rebecca Loos, who kissed-and-told after a “turning point” when she realised “Beckham’s double standards. After a meal for SFX employees at Madrid’s Hard Rock Cafe, Beckham did not leave a tip. The following day, the waitress gave Loos a note for Beckham. Explaining that she survived on the tips, she expressed her anger that someone as famous and rich could be so mean. After reading the note, Beckham was alarmed. ‘Give her this,’ he said handing over a thick wodge of euros. Reflecting in February about how Beckham had played her and lied to her, Loos was angry.” It doesn’t make a whole heap of sense on its own terms (how is that a double-standard, to fail to tip, realise your error, tip massively? How does that relate to Loos feeling played herself, or lied to? It’s the sort of foggy conclusion reached by a guy who thinks all pretty women do basically the same job).

The sex is a sideshow, anyway, to the book’s main thesis, which is that David and Victoria Beckham are obsessed with money, so they had to remain a “global brand [which] required constant public interest”. There’s a series of allegations about tax avoidance, decisions made either with only money in mind or the specific intention of gaining non-dom status: Beckham’s move to Real Madrid is the first; then his departure for America, which was puzzling in career terms, but was commonly agreed at the time to be a mercenary decision; there’s a bit of jiggery-pokery with a film financing scheme (which we actually covered pretty comprehensively, seven years ago ). And an extremely convoluted segment about a dispute with the German government. The furthest you could meet the author, particularly on that Real Madrid decision is, well, maybe? Or maybe he paid tax in Spain because that’s what quite a lot of international footballers do?

I probably learned most about the condition of Beckham-ness, specifically Victoria, in the chapter called Phony, and despite the author’s best intentions. The year is 2007, and Posh is launching herself in the US, with a $10m docu-series for NBC, which was later reduced to one hour from six and universally derided. Bower has a quote about what a princess she was from seemingly every person on the production, reams of detail about the show’s ersatz “reality” and amateurish screw-ups, verbatim derision from the press. What came off, though, wasn’t a scheming, Lady Macbeth “scantily dressed and oiled up, and wearing high leather boots”, but rather, a woman whose “brand” a broadcaster paid top dollar for, only to realise it had no substance. But was the cultural ire really justified? Or have Posh and, to a degree, David spent their lives as lightning rods for a rage against an emptiness that was in fact created by exactly the people who are raging against it?

One other detail counts as a revelation: that David Beckham’s knighthood was kiboshed, indirectly, by his wife. “The notion of ‘Lady’ Victoria irritated [former head of the civil service Bob] Kerslake,” he writes. She had too many houses, too many servants, also didn’t tip in restaurants. It’s a little bit rum – having a bunch of servants and houses has, historically, been the whole point of being a knight, so it feels class-coded, their offence being not the wealth itself, but that they weren’t posh enough (no offence, Posh) to merit it. It also doesn’t sound like the kind of thing Bob Kerslake would say.

Between the affairs, the all-night arguing, the conflict around their kids and how much media profile they should have (mainly when they were young), this does tell one amazing story: that the Beckhams are still married. They must, on some level, really like each other; but The House of Beckham is curiously, surely wilfully unenlightening about what personal traits either has for anyone to either like or dislike.

• The House of Beckham by Tom Bower is published by HarperCollins (£22). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply.