Watching a Sacha Baron Cohen comedy is like watching a gory horror film. He makes you shut your eyes, look away, squirm, sweat, cringe and groan in your seat as his unsuspecting victims — mostly members of the public — are spliced and diced by his merciless pranks.

Baron Cohen’s latest monster is an Austrian fashionista/television reporter called Brüno. He is gay, but the kind of gay character that popular culture tends to avoid. For Brüno is not your safe, sweet, Sex and the City, Will & Grace, goody-goody gay who’s a girl’s best friend. (Brüno is more likely to offer you a rectum to cry on than a shoulder.) No, he’s a male heterosexual’s worst nightmare: an in-your-face, down-your-trousers and up-your-wazoo, pre-Aids, hardcore, flaming faggot.

Given the similarities of structure between Borat and Brüno — both films feature naive foreigners travelling through America — comparisons are inevitable. For all his monstrosity, Borat’s innocence made him endearing, but there’s nothing likeable about the narcissistic Brüno. And this film doesn’t have a scene as funny as the one in the hotel between the naked Borat (Baron Cohen) and his assistant, Azamat (Ken Davitian). Overall, though, Brüno is funnier, grosser and, in some ways, more ambitious than Borat — though its flaws are greater, too.

Structurally, the story line of Brüno looks more improvised than Borat’s. The film begins with him crashing a fashion show in Milan and ending up sprawled along the catwalk. This gets him fired from his television show, so he heads to America to become “the biggest superstar since Adolf Hitler”. He tries acting and fails. Then he decides to be a celebrity, so, like Madonna, he adopts a black baby; then he adopts a celebrity cause, peace in the Middle East. And when this fails, too, he tries to go straight, to no avail. On the way to stardom, he encounters swingers, rednecks, Christians, a politician, Middle East terrorists and even actual celebs.

So, what starts off as a satirical exposé of the inanities of the fashion circuit — we see Brüno interviewing a model who says that she has “the hardest job in the world”; my dear, the turns, the turns — moves on to showing the conceit and stupidity of the world of cel­e­brities. You’d think that there was nothing left to say or show on that topic, but Baron Cohen and his crew give us the jaw-dropping sight of an American Idol panellist, Paula Abdul, being interviewed by Brüno as she sits on the back of a poor Mexican recruited from Brüno’s housekeeping team when his furniture goes missing, talking about the importance of her “human­i­tarian work”.

For all its mischievous fun, the film poses an interesting question: is Sacha Baron Cohen a great and brave satirist, as his admirers claim, exposing the stupidity, bigotry and hidden homophobia of our times? Or is he just out to shock and get a laugh?

I suspect it’s a bit of both. It’s when the film comes on all moral and high-minded that it grates the most. Brüno’s encounters in America make the point, over and over again, that there’s a lot of homophobia out there; but this is hardly a great discovery. And it’s interesting that he has to work so hard to provoke public displays of it.

The film may begin with swipes at the fashionable and famous, but its main attack is on the prejudices of ordinary people. But is Baron Cohen fair? For example, Brüno appears on a talk show with an audience of Afro-Americans and brings on his adopted black baby, who he calls a “dick magnet”. He then shows provocative pictures of himself and the child in a tub full of men where sexual acts are going on. The crowd get angry and are disgusted. But is that homophobia in action or a natural concern for the child’s welfare?

Baron Cohen’s film is informed by a liberal-minded simplicity that regards anyone who feels at all queasy about certain acts of gay sex as, ipso facto, homophobic. But the film gets to have it both ways:

it relies for its impact on the fact that you will be disgusted by certain acts, then turns around and accuses you of being homophobic. Its logic, however, is faulty, for when gays talk about the yuckiness of heterosexual sex — and, believe me, some do — they aren’t denounced as heterophobic.

I concede that Baron Cohen is about as brave as a comic could be without saving another person’s life. He is the one actor who does all his own stunts, even when they are as dangerous as walking around in hot pants among Hasidic Jews in Israel or taunting self-proclaimed terrorists in the Middle East. But isn’t it too easy to show up rednecks and God-fearing Christians as homo­phobic? Wouldn’t it have been bolder if Baron Cohen had shown the hidden anxieties we self-professed enlightened liberals have about gay sex?

That said, there’s no denying how funny Brüno really is. There are times when his earthy, gross-out humour takes flight into fan­tastic, surreal moments, as when he sees a swirling and talking penis in action. And the scene where Brüno goes to a psychic, then performs fellatio on the spirit of one of the pop duo Milli Vanilli, is one of the funniest and most disgusting things I’ve ever seen on the screen.

With Brüno, Baron Cohen has taken the comedy of embarrassment to a new and excruciating level. You leave the cinema drained, exhausted, delighted — and glad it’s all over.

18, 83 mins

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