Marianne Faithfull, Barbican, London

Looking absolutely tip-top tonight, is Marianne. Time Out once had the cheek to call her "mumsy" (though "in a glam, fantasy-older-woman way"), and the last time I saw her, she did have a maternal cleavage, which coincided with her cabaret-chanteuse, Kurt Weill era. Now, though, she's remanifested – rake-thin, with boyish hips and legs like pipe-cleaners. From where I'm sitting, her face looks like a cross between her early self and Zoë Ball. It probably helps that she's kicked heroin and booze.

It probably also helps that, on her new album, Kissin Time, she worked with young lads (and Dave Stewart). But that album's a mixed bag, and maybe the worst track is the Beck opener, with which she kicks off the concert. "Sex with Strangers" is insipid electro-funk disco, apparently inspired by the French singer Serge Gainsbourg. It's absolutely shocking, and not in a good way. As it grinds to a halt, Faithfull draws desperately on her cigarette and fishes out her specs to see the set-list. The air is suddenly filled with buzzing. "What's that noise?" she demands, balefully regarding the mixing-desk. "Darling, get rid of it. Now." The buzzing continues. "Is it me?" Shake of the head. "It usually is." Again to the wings: "What shall I do, Brian? Start the next song? All right. God."

The next song is an old one, the majestic and aching "Wilder Shores of Love", on which her phlegm-furred voice goes deeper than Darth Vader's. It ends. Buzzing. "We've still got that bloody noise." Hands on hips, she confronts her engineers. "I'm not going on till you fix that." While people cluster anxiously round the mechanics, Faithfull tells a joke, endearingly fluffing the punchline. Buzzing. "Just keep going, they say," she shrugs, having conferred. Almost to herself: "As usual." Story, of course, of her life.

"Brain Drain", her own down and dirty blues, is a snarling tale of user love: "You're a braaaain drain, you go on and on, like a blood stain..." Things start to come together. Until it's over, when there's buzzing. In a break to sort this out, we get another jokeand then off we go. Sadly, with another Beck number, "Like Being Born", a dirge-folk ditty. More dire offerings from the album follow. Why? There are some pearls on Kissin Time, so God knows which saboteur planned the show.

After a make-up break, she delivers Blur's groovy title track, a dubby, Dr John-type voodoo beast. Guest Will Oldham helps on a Waylon Jennings number; then Marc Ribot (the New York art-rock guitar genius, looks like Paul Auster) sets up a howling junkyard riff for "Working-Class Hero", which is so good you have to grit your teeth. At the end of that, Faithfull falls off her spike heels. ("Bugger it. They're not really for working. They're just for poncing about in.") Jarvis Cocker materialises to help on the vitriolic "Why D'Ya Do It?" and on the album track he contributed, "Sliding Through Life on Charm". It's profane, hilarious, and it suits her. Somehow, she's got through this evening by sheer force of personality. She could have made better choices. But, as this arch-survivor would be the first to admit, sometimes you just don't know till you've done it.