"I'D LIKE to introduce a special guest," said Kirsty MacColl, as she approached the end of her set. "Ooh, who can it be?" Well, it could be almost anyone, if the sleeve of her new Best Of compilation, Galore (Virgin), is anything to go by. It's a collage of commendations from one ex-Pogue, three ex-Talking Heads, and two ex-Smiths (Morrissey compliments her on her "crackin' bust") among others. MacColl is like a female Richard Thompson: the critics and the grown-up musos love her, the record- buying public are not so sure.

Maybe that will change. One MacColl fan told me that this time last year she managed to draw 20 people to the same venue, London's Mean Fiddler. On Friday there were people hanging from the people, hanging from the rafters.

As it turned out, the guest she introduced was her "champagne socialist" friend, Billy Bragg, who sang along to "New England" as if he he'd had a few champagnes too many. It is a Bragg composition, but it fits neatly with MacColl's own sharp-eyed tales of domestic depression and courage, of people kitchen-sinking without trace.

"They Don't Know", "Chip Shop" and the other hits (relatively speaking) were received with much appreciative waving of Guinness glasses, but the less well-known of her songs were often better. For all MacColl's bold- as-brass, tough-as-iron demeanour, it was a relief when the quieter songs allowed us to hear the soft, folky lilt and hint of husk in her voice. The set was almost Unplugged: an appealing, understated three-piece gave her space to breathe. It was when she had to sing loudly that she sounded like the girl who works down the chip shop. Her experimentation over the years has been admirable, but simplicity suits her best.

The music which overtured Shampoo's performance at London's Hanover Grand was an astute choice: the Beastie Boys' "Fight For Your Right To Party". Shampoo's hit single, "Trouble", is redolent of the Beasties in 1987: kitsch-loving superhero fans drawling witty lyrics about staying up late, accompanied by classic rock riffing (played by someone else). Perhaps, then, Shampoo too will be more than one hit wonderwomen. They're already performing to clubbers well into their twenties rather than the Smash Hits readership you might expect.

Wednesday was only their second UK performance since the release of the unambiguously titled We Are Shampoo (Food). Carrie and Jacqui marched on, more vacant than pretty, in their kitsch babydoll gear: all peroxide, pink and pig-tails, and T-shirts that have obviously shrunk in the wash. Their songs have the combination of toughness and poppiness which indie bands yearn for. Hearing the introduction to "Delicious", you could be forgiven for wondering if they were Oasis' younger sisters.

The real heroes are the backing band, particularly guitarist-songwriter- producer and all-round talented person, Con Fitzpatrick, and bassist Lee Christopher - who does indeed resemble Christopher Lee - a yawning glam- mod.

The trouble is that the backing musicians outclass the `Poo' (as even their press officers call the girls). It may be too much to expect them to sing, but it would be nice if they could at least shout in tune with each other. They have one tone of voice, and two poses - hunching forward while bawling, hanging back and stand-offish when they're not. If they are going to follow the Beastie Boys' trajectory, they'll have to come up with a couple more. And considering that their songs are about "going wild in the city late at night", how come they look so miserable? They don't say a word to the audience, but sulk and scowl until you feel like going home and putting on a Manic Street Preachers record for light relief. Sometimes blondes have less fun.

Sleeper must be the only band who offer greater pun potential to journalists than Shampoo do. My personal favourite, based shakily on Sleeper's squall of guitars and Louise Wener's politically incorrect sentiments, has something to do with pyjamas, PJ Harvey, and PJ O'Rourke.

But recently it seems as if a name suggesting lethargy has tempted fate as well as headline-writers. The name, as well as Wener's "Another Female Fronted Band" T-shirt, and the Costello/MacColl-esque lyrics of "Inbetweener" ("He's not a prince/ He's not a king... /He's nothing special/ She's not too smart...") now seem less ironic than they once did. After some great singles, ("Vegas", out on 27 March, is no exception), the unimaginative prodution of the debut album, Smart (Indolent) was a disappointment.

The concert at the London Astoria on Thursday did not restore much faith. Many of the perky pop songs seemed too complex for the band to manage, and they collapsed into a tinny mess of guitars. There were long gaps between songs and a lingering air of uncertainty. The band's best performer is the drummer, Andy Maclure, who could be the new Moon. The others stand around for a while until one of them starts bouncing up and down, at which point the rest start bouncing up and down too, for want of a better idea. For a group with some extraordinary material, it's all very ordinary. Even "Delicious" (not as good as the Shampoo song) was more of an unexceptional come-on than the clarion call to sexual revolution it has been. Wener is barely as sexy as a Blue Peter presenter: gorgeous as chipmunks go, but short on animal magnetism. And her voice, which has a rough'n'ready charm on vinyl, does not hold up at higher volumes (the next Kirsty MacColl, it's official).

In the future, Sleeper could well be one of Britain's best bands. But tonight's performance was a little... tired.

Kirsty MacColl tours in May.