There’s a moment when your musical crosses from the sincerity of jazz hands into something resembling an overwrought vanity project. Ordinarily, I couldn’t tell you when exactly; it’s not like there’s a line in the sand someplace. But Burlesque is the exception, because there it is, exactly 82 minutes in, when Christina breaks the fourth wall to look right at the director, as if to say “Jimmy, make me a star“.

Up until then, Burlesque comes across as a not altogether unlikeable rags to rhinestone story of a small town girl who dreamt big and got as far as the first rung of fame. Ali decamps to Los Angeles without a penny to her name (ignore the wad of cash stolen from her last job; the story works better that way), and circles the employment drain all the way down to Cher’s Burlesque club. “I wanna be up there!” Ali squeals with wide-eyed enthusiasm, as Cher the Mother Goose shooshes her away with a flick of her sequined feathers.

She’ll get there in the end; there’s always a Your Chance To Shine. But right now she shimmies across the floor as the club’s waitress, and watches as Nikki, the established act, grows more drunk and jealous of the young blonde from little Ohio. “I want her fired!” she hisses, “she thought I was a drag queen; the script awakening briefly to have Stanley Tucci retort “It can’t be the first time you’ve heard that”. If Nikki sees the star presence, then Cher certainly doesn’t, and begrudgingly allows Ali an audition only after she does her very best Oliver plea, a tap-dance and dipped hat away from “I know the routines pa! Oh boy oh boy just give me one shot! I swear you won’t regret it mister!”

Ruthless ambition sees her star in the ascent, and with it comes the will-they, when-will-they false dilemna of her Perez Hilton love crush, whose fortune cookie wisdom of “Life… is the choices you make” signals the second act, in which a devilishly charming developer swoops in to buy the club. He wants to take everything Cher’s worked for! No, she cries, I’ll never give in! But what’s this? The rogue has his eye on Ali, on whom the entire performance and thus fate of the club rests. If I was to tell you she blindly falls for him against all advice, might you tell me what happens next?

Whatever the pre-ordained outcome, first must come a risible advert for Christina the brand, which is even more contrived on film than it sounds. In covering similar ground, Coyote Ugly and Chicago at least had the decency to put their spirit fingers to use in furthering their plots. But as Burlesque’s 82nd minute rolls round, the fear your cynicism for the movie was misplaced fades away, and a literal 30 minute music video takes over the narrative: it’s Christina dancing and singing to what may as well be actual Christina songs from actual Christina albums. And wouldn’t you know it, there’s a soundtrack for sale.

As the Chinese water torture continues, one of the numbers even drops the pretence of being loosely about the club to focus entirely on its shy star, bathing her in a spiritual blue light that shows it to be her moment for overcoming adversity and succeeding against the odds. You can just taste it, can’t you? Poor old Cher finally gets a look-in with a solo to show there’s life in the scrapped-back, pinned-up goat yet, but otherwise the Christina show rolls on without interruption.

The movie’s poster proudly – and, presumably, without irony – proclaims “It takes a legend to make a star”, but there’s barely a moment when Christina’s Ali isn’t a star. Once she is allowed to set foot on the stage, the movie ceases to chart her rise and merely observes, as if your movie ticket was just to see MTV beamed from the projection booth. Even the finale, intended as the emotional payoff to a subplot of Perez trying to write a hit song for Ali, is a limply choreographed number that has nothing to do with the film or its characters, played to a tune so lacking in insight or melody that I can only imagine the composer hitting ‘Demo’ on his Casio and calling it a day.

A similar process was likely responsible for the script, which somehow bounced between three separate writers (amongst them, Juno’s Diablo Cody) without any of them being able to inject anything memorable or biting to lines that alternate being vacuous cheerleading and puffed-up emotional hokum. It is amongst the least characterful scripts I’ve been witness to, and that its words are given to both the vacant Aguilera and to a woman so youth-obsessed at 64 that she now can’t move her face is, you have to say, quite fitting.

As you leave the theatre, you might stop to consider the song that plays over the credits. The last hurrah of the production team, their triumphant pièce de résistance? “It’s the beautiful, beautiful, beautiful, beautiful, people they want. It’s the beautiful, beautiful, beautiful, beautiful, people they fall. It’s the beautiful, beautiful, beautiful, beautiful, beautiful, beautiful people they love”.

Equally fitting.