The Suicide Squad is, in all but name, a sequel to David Ayer’s 2016 critical catastrafuck Suicide Squad. DC is desperate to wipe the slate clean – we know this because the title is preceded by the definite article, a promise to get things right the second time round.

Scarcely any remnants of the first film have been retained, except Margot Robbie’s Harley Quinn, whose solo spin-off Birds of Prey was a welcome break from the gloomy streets of Gotham. There’s also Viola Davis reprising Amanda Waller to provide villainous exposition aplenty as she recruits a new band of miscreants to do the US government’s dirty work.

Of course, there’s a precedent for messing things up at DC. We now have two versions of 2017’s Justice League: an abysmal two-hour snoozefest from Joss Whedon and a grey-washed, double-length “director’s cut”. The release of the latter has even inspired a not-in-any-way-laughable #ReleaseTheAyerCut campaign, which claims that Ayer was prevented from developing his opus by money-grubbing studio execs. Maybe they’ll keep quiet now Warner Bros has supposedly given the fans exactly what they want.

Attempts to canonise Zack Snyder as an auteur have been extended to The Suicide Squad’s marketing campaign, with “The horribly beautiful mind of James Gunn” cited as the film’s source. This is a knowing statement – Gunn joined the project after being fired from Disney, where he was developing the Guardians of the Galaxy series, for a number of old tweets in which he made jokes about 9/11, paedophilia, rape, and the Holocaust.

While Gunn has said those “jokes” were borne of provocative immaturity, it’s exactly the sort of humour The Suicide Squad runs on – rain is described as “angels’ splooging”, John Cena’s Peacemaker is told to “eat a field of dicks”, and so on. It’s about as anti-woke as you could possibly fathom, and there’s a complete disregard for what might be offensive to some viewers.

One of the biggest problems with 2016’s Suicide Squad was that you didn’t care about any of the characters. There’s a baffling dichotomy in The Suicide Squad of villains who are entirely expendable and those who seem to be indestructible. Sylvester Stallone fills in for Vin Diesel in the monosyllabic Groot role as King Shark, who is shot, eaten alive and crushed by several buildings, while others explode in a splatter of guts at the slightest touch. Gunn seems to have recycled a lot of the gags from the Guardians films with a few more F-bombs dropped in to reassure us that this is an “adult” movie.

Gunn does try to give his characters emotive, relatable backstories, but it always feels heavy-handed. We meet Idris Elba’s Bloodsport in prison where he’s being told by his daughter what a bad father he’s been. Daddy issues is a running theme – newcomer Daniela Melchior became Ratcatcher 2 to follow her dead father’s footsteps. It’s no wonder their relationship was messed up – the camera pans to reveal he’s Taika Waititi. Melchior gives the most compelling performance, although every time she shows human feeling she’s mocked by Bloodsport or Peacemaker as a “Millennial”.

Quinn, the Squad’s only other female member, is treated with similar disregard. Unlike Cathy Yan’s multidimensional depiction of the character in Birds of Prey, here Robbie is reduced to the object of a pubescent boy’s masturbatory fantasies. She spends most of the film tied up, and is hyper-feminised by Corto Maltese dictator Silvio Luna (Juan Diego Botto) in a red ball gown which becomes increasingly eroticised as it’s torn apart.

We’re supposed to buy that Quinn could suddenly be convinced to settle down and live like a princess to accommodate the film’s totally unnecessary sex scene. Suddenly she’s kicking colonial butt, squeezing men’s heads between her thighs, before being reduced to being the second stupidest character next to the shark guy. Such erratic characterisation is exhausting, and symptomatic of The Suicide Squad’s insistence on being a mind-numbing sensory assault.

Stylistically, The Suicide Squad looks nothing like its predecessor. The first half is shot like a 2000s sitcom, replete with Peter Capaldi reviving his Malcolm Tucker-glare as The Thinker. The second goes full-blown kaiju (we know this because someone says it), with a monster villain described at the start as being like a butthole, even though in actuality it resembles a collection of vulvas. The Suicide Squad is crass, noisy and brash – a disturbing glimpse inside the mind of James Gunn.