Måneskin’s frontman Damiano David stares out into the vastness of the O2 Arena, raising his eyes to the seats at the rear, so high up that tickets come with a warning about vertigo. “Fuckin’ ’ell,” he says, almost to himself. “This is a big-ass venue.” David is not a performer much hampered by reserve – it takes him two songs to strip to his waist, and a couple more to start grinding his crotch against the microphone stand while singing “I want to fuck” – but, for a moment, he seems genuinely taken aback. Few rock bands have taken such an unlikely route to arena-packing success, involving busking on the streets of Rome, Italy’s version of The X Factor and Eurovision, a pathway that doubtless says a lot about the by-any-means-necessary approach an Italian rock band has to take to get noticed internationally and may also tell you something about the ongoing collapse of old-fashioned ideas about credibility and authenticity in music. As well as giving David an opportunity to briefly reflect on how far they’ve come, their O2 gig answers questions about who has fuelled this success: judging by the audience, it’s largely late teens and twentysomethings, marginally more female than male, and with little about their appearance that reflects Måneskin’s own stylistic devotion to glam rock. Up on the stage, it’s a riot of flared leather trousers, hot pants and platform boots, plus a sparkling cowboy hat that guitarist Thomas Raggi – to reach for a glam-era comparison, very much Måneskin’s equivalent of Dave Hill from Slade – spends the opening songs endearingly struggling to keep on his head. In the crowd, it definitely isn’t. But you shouldn’t confuse a lack of interest in sartorial cues with a lack of devotion: normcore or not, Måneskin’s audience are strikingly rabid in their affections. Dispensing with both of your best-known tunes – the Eurovision-winning Zitti e Buoni and a cover of the Four Seasons’ northern soul favourite Beggin’ – early on in the set is a bullish move, but no matter. Belying its respectable, rather than spectacular sales, the audience seem to know the contents of Måneskin’s recent album Rush! by heart. Whenever David stops singing midway through a line and turns the microphone to the audience, there’s never a muted response: they loudly fill in the lyrics word-perfect, even when the lyrics are in Italian. Their sound, meanwhile, is noticeably heavier live, the guitar solos longer, the debt to Franz Ferdinand and the Killers less pronounced and the deficiencies in their English lyrics – which tend to boilerplate expressions of vague rebellion and stuff about sex that’s never terribly sexy – less obvious: David delivers the most hackneyed lines with a camp flourish that suggests he can’t take them seriously either. The ballads, meanwhile, are more clearly linked to the lighters-out anthems that were an essential part of any 80s hair metal band’s arsenal, which in turn makes their association with Swedish pop auteur Max Martin – who co-produced Rush! and had a hand in writing the prettiest ballad number they have, If Not for You – seem less like commercial opportunism than a meeting of minds. Before he started knocking out the hits for Britney and Katy Perry, Martin was a member of a hair metal band himself: you suspect he gets Måneskin perfectly. So, audibly, do the O2 audience, whose enthusiasm never lags: after an hour and half, they’re still greeting everything as if it’s the band’s greatest hit. Watching David bump and grind, or Raggi engaged in his ongoing struggle with his hat, you understand why: it’s ridiculous, depthless, hook-laden fun, and the band behind it are intensely likable. If that sounds like faint praise, it isn’t intended as such. Enthusiasm quite as communicable as Måneskin’s is a rare commodity in both rock and pop – deemed uncool in the former and micro-managed out of the latter, it’s a strangely heady thing.