Instead tonight has that awful feeling of an artist on the slide - despite the thousands of fans here to see the self-proclaimed ‘God of Fuck’ do it to them one more time. The girl in the ‘Jesus Is A Cunt’ T-shirt; the boy with sugar-red horns on his forehead; the V-shaved scalp of some piss-haired youth domed like an alien reject from Star Wars (the new series); the corsets and witchery; the sustaining Goth romance and zest for getting made-up, be you boy or girl or somewhere inbetween; the lonely slobs in bad T-shirts empowered by a little ‘grotesk burlesk’ anger…

It’s easy to poke fun at a Manson audience – and by dint of that Manson himself – but there’s something phenomenal about a creature who can gift imagined identities to people whose dreams are almost always cheap and second-hand and tamed. Manson has penetrated the mainstream with something wilder it’s true - "we’re all stars now". These people love him for it.

The boy who was once Brian Warner must be thrilled looking out at his kingdom cum: from adolescent misfit to wanna-be rock journo to struggling Goth rocker and Trent Reznor protégé, superceding the angst master to become a huge theatrical force in his own right. Next stop, appropriately enough, the role of Willie Wonka in Tim Burton’s remake of Roald Dahl’s Charlie and The Chocolate Factory. Maybe there’s a life left in him yet.

Religious and moral minorities continue to be outraged, though Manson’s not the icon of evil he once was. Journalists prefer to mock him, as if being intelligent and histrionically popular are simply not allowed. Either way – outrage or mockery – Manson has been able to soak up the attacks and thrive. Till now.

But tonight the slide is clear. A slide all the more disappointing for an artist I expected to so much more from. Comparisons to David Bowie and Alice Cooper at their peak are certainly misplaced. Manson lacks Bowie’s chameleon gifts and the musical radicality that accompanied them from Ziggy Stardust to Young Americans and beyond; nor does he have Cooper’s grand melodic abilities, the wild range of a Billion Dollar Babies or a Welcome To My Nightmare.

Instead he ploughs an old field again and again, till the yield all but fails him. You can see this in the cut-down stage show that looks a little impoverished; in the repetitive, sludgy, techno-pop with a shrill metal edge from a band that never lets up, never; in the Weimar Republic styling, the lewd dance girls and goose-steps which suggest decadence and, tsk tsk, Nazism.

More than anything it’s the obviousness – and that’s Manson’s most boorish crime after a decade at this fantasy – the obviousness in everything he does, the crude levels he so willingly stoops to get attention: the look of the band, all Aryan and blonde while he remains in pure Transylvanian black; the third-rate Satanism that has given way to Nuremberg meets Salem imagery (a hint, perhaps, of incipient contempt for his own audience); even the Mickey Mouse ears given an S&M fetish spin (actually not a bad idea).

Late in this night of hard, dull grind for the ears, Beautiful People finally shows a flash of bumping tribal energy. Doll-Dagga Buzz-Buzz Ziggety-Zag also shows some manic distinction and humour too. Tainted Love is just awful, completely unambiguous; Sweet Dreams fares better as a cover, interestingly enough because of the lyrics. It’s the constant musical bludgeoning that kills off everything in the end, however, transforms every tale into one deep, dark pile of electro-rock sludge.

If Manson were to apply the same textural contradictions to his music as his paintings, watercolours similarly obsessed with sex, death and fascism, we might find some greater mix of beauty and pain and even queer menace truly emerging. But Manson is chasing what he had, not exploring who he is. And that’s the sad, wonderful, frightened story of Brian Warner left still wanting and only glancingly hinted at: "We used to love ourselves, we used to love one another."