There are few experiences in cultural life that can shake one's faith in the basic good of humanity, but sitting among 10,000 free-willed citizens who have paid £23.50 to watch blood-draining, pulse-stopping karaoke just about does it.

It's hard to pinpoint the exact moment when it becomes clear that all hope is lost. It could be spotting H from Steps posing with one rejected contestant, "the chicken man", during the interval. Or perhaps it is when the timid girl from Two to Go attempts to act less like a newly qualified primary school teacher by letting out a mid-chorus whoop. Probably, though, it is the moment operatic manband G4 launch into Radiohead's Creep and several thousand off-duty mums in pink cowboy hats and glittery ponchos yell along as the band change the words to: "What the hell am I doing here/Singing at Wembley." Tears of impotent despair are the only sensible reaction.

The stage version of a TV "talent" contest was never going to be high art, but this ... this is horrible. Each of the nine final acts from the series gets a look-in, presumably to ensure that everyone who ever voted for anyone will buy a ticket. They perform in order of popularity, which means that much of the audience is sending text messages during the first four or five, only looking up at the big screens to watch the excruciating backstage "sketches" prerecorded with presenter Ben Shepherd.

What links each act is the belief that the louder they sing, the better they sound. Worse: the audience has been brainwashed to agree. They lap up the awful unoiled-door noises that result when Hollyoaks doppelganger Roberta and blonde divorcee Verity work their key changes, and go mad when queen bee Rowetta opens her cavernous lungs on Over the Rainbow.

Perhaps most embarrassing of all is crowd favourite Tabby, a 23-year-old "rocker" from Ireland who looks like a cross between Grange Hill misfit Danny Kendall and the Artful Dodger. Both old and young enough to know better, Tabby covers Sweet Child o' Mine, plays his guitar behind his head and, Lord help us, unleashes one of his own songs.

Then there is the winner, Steve Brookstein, a man who only got to number one after announcing his intention to give away the "profits" (ie the 10p and packet of crisps left over after Simon Cowell took his wodge) to the tsunami appeal. He is smug, sweaty, covers Phil Collins and claims to feel "blessed". We are all cursed.