Miley Cyrus, O2 Arena, London

When a 17-year-old singer from the Christian right holds such sway over young minds, pop has to be taken seriously

Watching my first-ever episode of High School Musical the other week – oh, the ordeals I put myself through in the name of research – I was stricken with a dizzying attack of the cultural bends.

When I was what would now be termed a "tweenager", teatime drama representing one's own peer group involved British schoolkids taking heroin in toilets and getting embroiled in racist bullying. Ten years into the 21st century, it involves Dulux-fanged American teens making glib "talk to the hand, whateverrr" wisecracks on cruise ships, and the occasional challenging use of the word "fart".

There are people – the same sort, by and large, who read Harry Potter books despite having passed puberty some time ago – who keep telling me I ought to "lighten up, it's only pop". A fatal error, which both underestimates both pop's preciousness, and its power. It's never "only pop".

The poster girl for the current Disneypop phenomenon is Hannah Montana herself, Miley Cyrus. In case it's unclear, she's the one who hasn't been disgraced with nudie photos (although she did do an implied-topless Annie Leibovitz shoot for Vanity Fair). Indeed, so sexless is the squeaky-clean 17-year-old that the very idea feels profoundly wrong. And while the twiggy teenager may not look as if she's a member of an imperialist shock-troop, in terms of exporting the conservative values of the Christian right she's more effective than the marines. You think I'm exaggerating? Time Magazine doesn't. It put Miley Cyrus in its Top 100 Most Influential People list.

Perhaps I'm not the only one with misgivings. Perhaps you, too, felt a rush of vertigo on Christmas morning when your beloved offspring opened her Hannah Montana calendar, Britannia High duvet cover or Camp Rock lunch box. Perhaps you even gave in to Pester Power and took her to one of these O2 concerts, and experienced a faint, nagging feeling of "Has it come to this?". More likely, you just shrugged and thought: "Well, it's what she wanted."

Giving in is all too easy, as the stats show. Miley has achieved the kind of success of which her mulleted father Billy Ray could only dream, earning upwards of $25m a year. Joe McElderry's cover of her song "The Climb", tonight's sickly climax, is the UK's first No 1 of the new decade, despite the temporary delay caused by the RATM stunt. In the end, the likes of Cowell and Cyrus will always prevail, raging on behalf of the machine.

Cyrus's popularity among the supine, spoon-fed sofa-spuds of British youth is so intense that, even though she's playing seven nights in a 23,000-capacity enormo-dome, her record company couldn't find any room to squeeze in one critic (hmm). So in order to provide you with dispatches from the front line we bought our own ticket. And I can exclusively report the earth-shattering news that Miley Cyrus makes Avril Lavigne look like Siouxsie Sioux, such is the accelerated spiral we've taken down pop's plughole over the past decade.

It's an unremarkably generic, high-spec/low-com-denom arena show, filled with material, written "by" (read: "with", in the change-a-word, take-a-third sense) Cyrus herself, which consists either of melismatic ballads or putrid pop-rock like "7 Things", with a recurring Nashville twang to remind us of her parental heritage.

The cheesy sub-Rednex hillbilly pop of "Hoedown Throwdown" is interrupted by the face of from Black Eyed Peas, and we're treated to a few seconds of "Boom Boom Pow". Now, the jury's still out on what this is exactly, but whatever it is, I'm pretty sure Cyrus doesn't have it.

The show's most expensive stunt involves Cyrus riding a flying Harley Davidson over the heads of the Stepford Tweenies below and singing Joan Jett's version of "I Love Rock and Roll", while pseudo-edgy tattoo art flashes stroboscopically on the big screen. Of course, Miley Cyrus Inc. would never endorse actual tattoos.

The Disney/Cyrus tyranny doesn't look like ending any time soon. With every minute that passes, the sensation of "Must we throw this sanitised saccharine slop at our kids?" is ever more overwhelming.

Tips for 2010

By Simon Price

Lady Gaga: The new Queen of Pop – the single greatest thing to happen to the genre this century – gets her freak on for her bedazzled subjects. MEN Arena, Manchester, 18 Feb, then touring.

Muse: The pomp-rockers' supremacy as a stadium act is now so secure that their autumn gigs at Manchester (4 Sept) and Wembley (11 Sept) are spaced far enough apart to accommodate even more shows. That's confidence for you.

Sonisphere: The new challenger to Download as the summer's premier rock/metal fest gets serious in its second year, with Iron Maiden, Placebo and Rammstein heading an impressive bill. Knebworth House, Stevenage, 30 Jul to 1 Aug.

The X-Factor Tour: Love it or hate it, more people will pay to see Jedward & co than any other tour in the early months of 2010, with matinee shows squeezed in at weekends. Liverpool Echo Arena, 15 Feb, then touring

Faces to watch:

Look beyond samey tips lists, and instead investigate Foxy Shazam, the insanely entertaining Cincinnati rock'n'soul six-piece who are guaranteed to blitz the festival season, and classy Brighton electropop quartet Mirrors