This must be every metrosexual's worst nightmare. Here I am at a fashionable spa, naked as the day I was born, covered head to toe in a verdant goo known as spirulina - and the water has stopped working.

I can't wash it off. Spa attendants and beauticians shuffle around anxiously. I will remain coated in this stuff for ever, a lurid green merman in a state of perpetual detoxification. Perhaps I will become so detoxified there will be nothing of me left?

Before you send the newspaper windmilling across the Tube carriage, harumphing that any man who has a spirulina wrap deserves this indignity, I should point out that I was at the spa by accident. My fiancee came by some complimentary his 'n' hers treatments and I decided to offer up my body this once, in the spirit of research. I'm told these places are all the rage in our capital.

Before we began our treatments, we were given questionnaires to fill in to the gentle strains of an indoor waterfall. Do I have a regular skincare routine? Occasional showers. Which brand of skin product do I use? Thames Water.

Then we separated. I was to strip off and undergo a vigorous exfoliating sea-salt scrub; a full-body moisturise; and the aforementioned daubing in spirulina, which may sound like a venereal disease, or possibly an evil ballerina, but is in fact a kind of sea algae renowned for its restorative properties.

This weed would rid me of all impurities, including, it is hoped, any impure thoughts towards the obliging young slip of a girl who was slathering the stuff on my naked body. My fiancée was in the adjacent room, having the same done on her by, presumably, a well-hung and randy young hunk.

Thus coated, I was cocooned in a sort of surrogate womb known as a flotation tank. Twenty minutes of this were apparently equivalent to four hours' sleep. It was after this that things started to go wrong, as I attempted to shower the green stuff off and found no water forthcoming. My girl was visibly panicked but dealt with it impeccably, merely returning me to the flotation tank for a further 40 minutes as the spa technicians paid the water bill and H2O was restored.

What ran through my mind in that cocoon?

Hazy childhood memories. Disconsolate feelings of loneliness. A blissful kind of panic. Go to a hammam in an Arab country and such cleansing routines are performed communally and vigorously; in London, those who can afford it are locked away alone and quiet, with only their thoughts for company. Then again, I suppose if you are willing to pay for this kind of wheeze, you can't have many thoughts in the first place.

[This is a (slightly expanded) London Life column, published in the Standard yesterday - gratifyingly, I have just had a phonecall from an anonymous Selfridges employee telling me of the great pleasure taken in the article by the shop floor staff - and the fury of the management]

Is there any ordeal more dispiriting, more dehumanising, more wretched than shopping in Selfridges?

No.

But for some reason I again found myself alighting at Bond Street and wandering into the place last week. I thought it might be more bearable than normal this time, as I knew more or less exactly what I wanted: a purse (black, oblong) for my fiancee's birthday. I could picture the thing in my mind and Selfridges, which once had a reputation for quality, seemed to be the place to find it.

But Selfridges no longer lends itself to buying anything specific. It now sells itself on experience rather than practicality. So the simple question: "Where would I find a purse?" Is met with the answer: "Everywhere and nowhere" - and you must traipse from stall to dispiriting stall, deciphering the semiotics of branding assessing the gaudy trinkets offered by Louis Vuitton or DKNY.

The shop is therefore aimed at people after Chanel or Gucci as opposed to, say a scarf or a shoe. And what strange creatures these people are; generally young, in couples, with a holiday sort of air to them, a vacant look and indeterminate foreign accent. Perhaps the children of the non-domiciled foreign businessmen who have recently turned our city into their private playground and whom the government are so keen to protect. Watch them buy a chocolate fountain and a pair of Prada loafers: these are the people safeguarding our economy. What do they dream, I wonder, when they go to bed at night?

Having been physically sick at the Versace franchise, I wandered into the more affordable "High Street" bit, full of native females perusing brands such as Oasis. I generally consider myself a bit of a feminist, and I like to think it is this instinct, rather than visceral misogny, that so pains me at the sight of the feminine hordes, fighting eachother for shoes. I would seriously contend that the average British female has no conception of how ugly she looks when shopping.

But she is a victim compared to the staff, who are paid solely to patronise you. All shopping is vile to a degree; but at least a well run store (such as John Lewis) does not assail you with the obnoxious slogans, competing soundtracks and painfully slow escalators. Before you know it, you are in the Smythson's section, wondering plaintively why an ugly green passport holder might be worth £150, then realising that after an hour, you are still empty handed. Unable to face starting again in a new shop, I plumped eventually for a Mulberry purse. Was it what I wanted? I didn't know anymore.

"This is absurd" I said treafully to the cashier as I handed over my card, abject. She pretended not to hear.

"You have coffee with a girlfriend, you get your beauty treatment, your laser or your Botox, and then you buy yourself a gorgeous dress", is how the store's creative director Alannah Weston describes the Selfridges experience. The revolution cannot come soon enough.

Were some alien species to alight on a London concert hall - a hyper-intelligent hippopotamus, for example, or a human being under the age of 60 - they would be doubly confused.

First, by the unusual contract between audience and performer, which states that it is perfectly okay to whoop and holler at the end of a concerto, but never between its movements. This seems strange at first, especially if you're used to attending pop concerts where whoops and hollers are encouraged at all times. But the principle is sound: the silence is essential to the music, marking a change in mood and rhythm, and why should one huzzah ruin the quiet contemplation of everyone else?

The second point of confusion is a knottier problem. Instead of clapping in those short gaps between movements, the audience clears its collective throat. The first concert in Daniel Barenboim's ambitious Beethoven sonata-cycle at the Festival Hall last week was a case in point, 'case' having the appropriate medical ring to it. The January chill helped create a veritable cacoughany, as, between movements, the crowd released all the throaty vexations they had been nursing through the music.

One minute you were in rapt meditiation, admiring the Israeli-Palestinian maestro's instinctive rendering of the Hammerklavier; the next you were in a tuberculosis ward, gratefully fingering your BCG scar. What our hippopotamus would have made of this spluttering tribute I don't know.

The next morning, one reviewer commended the crowd for their concentration - not one cough during Barnboim's actual performance - but I wonder whether the odd wheeze here and there would have been preferable to the unnatural tirade.

Some concert halls have 'experimented' with cough sweets - but my colleague Norman Lebrecht warns of their attendant perils, recalling a Mahler's Ninth ruined by the scrunching of wrappers. He suggests spitoons of the things, unwrapped, at the end of each aisle, but this strikes me as a short term solution at best. Surely it would promote a free mingling of germs that would soon kill off the core audience? Bsides, the noise of sucking sweets - much like the sucking of false teeth that is a peril of watching opera at the Coliseum - is irritation itself.

Ordinarily, I see no good reason why concert and opera houses should feel obliged to bring in a younger crowd. Perhaps this is one?

But even I finally succumbed, tearfully clearing my throat in the final piece having held out so courageously. My fiancée bit the dust long before. Which left just one man unafflicted by the mania: Barenboim himself. Though judging by the gusto with which he mopped his brow, I think he feared the worst.

* Barenboim: Beethoven Sonata Cycle continues at the Festival Hall (0871 663 2500) until 17 February