If You Liked School, You'll Love Work By Irvine Welsh Vintage, 28.30, 320 pp

ONCE, Irvine Welsh novels were cool, outrageous and did just what they said on the cover. Trainspottingmade geeks of a generation, reciting the "choose life" speech like a mantra. Marabou Stork Nightmares profoundly disturbed the sleep. Porno was . . . well. . .

Perhaps because it inspired so many imitators, the gross-lit genre now seems a bit jaded. Maybe Welsh should have let his fiction mature at the same genteel pace as its author, who has now given up the hard-living and found himself a lovely girlfriend. It must be a strain to keep up that "man ay the peeple" voice now that he has chosen fixed-interest mortgages, leisurewear and matching luggage.

Whatever the reason, this latest collection feels a little like going through the motions. Welsh turns his usual tricks, and you can't say he isn't trying. We get the young, laddish voices: this time in Californian and Cockney as well as brilliant, brain-aching Leith. The gross-out content is sicker than ever. But somehow, seeing an older, wiser Welsh madly ramping up the scatology is a bit like finding your parents have joined Facebook. Why not turn his undoubted wit and dexterity to grown-up matters instead?

Take the first story, 'Rattlesnakes'. California drop-outs Eugene, Scott and Madeleine are driving across the desert with an epic comedown. Eugene's predatory ambivalence towards Madeleine is fantastically creepy.

But Welsh's trademark ventriloquism fails when they open their mouths. One minute, we hear three average, educated Brits.

Then, Eugene exclaims that "a rattlesnake bit my cack!" Similarly patchy dialogue appears in the title story, in which expat Mickey runs a bar in the Canary Islands, inexpertly shags three equally unpleasant women and randomly exclaims "fark!"

Welsh's writing has been described as misogynist, but here his women are far more convincing. 'The DOGS of Lincoln Park' is also peppered with disjointed Americanisms, but the characters are gleefully repulsive. "It must be terrible living in a war zone, Stacie shudders. . . . It's kinda what they choose, Stephanie asserts. . . . If they don't like it, they can get off their butts and leave, like our forefathers who came here did." You think they might be lame caricatures . . . and then you remember Paris Hilton. Welsh is back on form, even, with 'Miss Arizona', a Roald Dahl-esque tale of a dotty taxidermist, whose ending is no less satisfyingly chilling for being blindingly obvious from the start.

Only here is his hero . . . a middleaged ex-boozer, like Welsh . . . dead real, and has a lovely line in metaphor: who'd not love "a darkeyed beauty, finer than frog hair"?

Unfortunately, the thrill of these pleasing similes is completely deadened by those in the final story, 'Kingdom of Fife'. At his best, Jason is vintage Welsh: "That's young c**ts fir ye, " he says, philosophically. "80 per cent ay thum'll grow oot ay it, the other 20, well, that's why yuv goat prisons ' cemeteries ' drug overdoses." At his worst, with his onanism and "hoor" metaphors, he's a parody of the author.

It is a shame that wee Jenny Cahill, the horse-loving object of Jason's desires, is not given more room to develop. She is funny and smart, a well-fleshed out character in more ways than those appreciated by Jason. Instead, the story is awash with beer and bodily fluids.

Welsh devotees will no doubt find much to enjoy in this mucky collection. But if you liked school, you may find this too much like hard work.