THE thing about art is that it is always swallowed by money. For a while it can lead the debate, surprising and confusing us in varying degrees, persuading us that we have brushed against some inner truth.

But time moves on, the art market kicks in heavily and before you know it last year’s shocking radical is this year's fast-emerging must-have and the slide into bourgeois respectability, second homes, private education for the kids and benign magazine profiles begins. Something similar happened to Pop Art a long time ago, and this is why I can’t help hearing the clink of hotel cocktail ice whenever I find myself looking at a Warhol, Lichtenstein, Rauschenberg or any of the others.

Walk into Coskun Fine Art’s exhibition of American Pop Art in Cork Street and you can tell at a glance that this is a show designed for the yacht set in town on shore leave. Strewn around the gallery are complete portfolios of Warhol’s Jewish Thinkers, the Mao series, little trios of Tom Wesselmann drawings and the odd Picasso just for fun.

Now there are yachts and yachts, but Gul Coskun’s hard-hitting strategy has been to put together enough top-grade works of different sizes and media by the best-known artists of the mid-to-late 20th century that even the owner of a moderately smart dinghy should find something he recognises.

“They’re all blue chip,” stresses Coskun, a petite, carefully blonde denizen of the sundeck. “Look, isn’t this the most fabulous drawing?” She gestures towards a small pencil drawing by Wesselmann. It is beautiful and perfectly finished in that super-controlled way of his. I can’t remember if she mentioned £20,000 or £30,000 but the tone said it all: peanuts, darling, really.

In Coskun’s elegant house the walls teem with Warhols, Picassos and Lichtensteins, some of which will make the short journey to Cork Street. I don’t know what to make of the iconic image of lesbians opposite Coskun’s four-poster bed, but then I’ve never warmed to Lichtenstein’s cartoon style. Downstairs, most striking of all is the giant Warhol black diamond-dust-covered image of shoes that spanned the best part of an entire wall in the sitting-room.

This is a dark, twinkling work in which the inconsequential is transformed into a votary object, where a fetish (shoes) is layered over by an addiction to “magic” dust. The jump between the banal and the overdone is something that many marina-boys will appreciate, so it’s bound to sell.

Coskun tries to enthuse me about the Marilyn painting on the easel in the corner but you are either dazzled by celebrity allure or you’re not. In any case, Warhol territory is tricky — how can you trust if an image is by Warhol or not? Trust is something that Coskun, who admits that most of her job involves reassuring clients about what they’re buying, holds dear: “No gallery can issue a certificate of authenticity as these have no validity. It would be similar to me issuing a visa to the US — it has no value. But we have a very good section on our website which gives a good background on buying.”

Aside from actually purchasing a Pop Art work, there’s the arguably more important issue of whether we conceptually “buy” it in the first place. I suppose this happens to all art after a while, but now that Pop Art has been going for more than 30 years — Peter Blake keeps the flag flying for Britain, but it’s an increasingly lonely task — I’ve grown tired of its blandishments, its exhortation of the temporary, the cheaply made, the gleeful interest in extreme fame or utter ordinariness.

Warhol’s interest in super-famous people was, I’ve always thought, so imaginatively lame, but then his genius comes through his films, such as Empire, a long watchful stare at the light changing on the Empire State Building. It’s this element of time, of its chromatic, emotional subtleties, that I find missing from so much Pop Art, but which makes me ultimately think that while Warhol should never be trusted, he was brilliant.

The bigger problem is that while Pop Art originally turned the tables on high art, making the banal significant and the ugly sort of beautiful, the rest of the world has not only since caught up but left it far behind. There isn’t much produced by advertising today that isn’t influenced in some way by Pop Art, but it seems to me that contemporary art practice has resisted the obliteration of meaning and the erasure of personal intent that Pop Art rejoiced in, and now finds itself absorbed by, the allure of personal significance and the immersive experience.

Glamour, something Pop Art found slumped in the back of a nightclub at 3am, is now much more self-protective and alert and is more likely to be caught detoxing than drugged out. If Pop Art once looked out and out into the wider world, risking conceptual dissolution, then contemporary art now is heading in the opposite direction, to an inner place where the consequential, not the inconsequential, matters.

Pop Art’s Big Bang is in retreat, its once carefree brightness dimmed by new fears as the world darkens. The great irony is that while so many Pop Art images play on the supposed distance between high and popular culture (a distinction that may have meant something in the 1960s but which means almost nothing today), they are now subject to the kind of connoisseurial anxieties once common only to museum-grade “old” art. They’ve become marooned in time, super-precious and fully tamed. Coskun’s show offers them a sunlit, glorious retirement.

• American Art from 1960 is at Coskun Fine Art, 23 Cork Street, London W1 (020-7581 9056), from Sept 2 to Oct 1 (www.coskunfineart.com)