Tuesday morning, about 11 o'clock at the Royal Academy, and it's absolutely heaving. The show of Turner's watercolours has only been open for a couple of days, but plenty of people seem to have decided to fit in a show along with their Christmas shopping.

Tuesday morning, about 11 o'clock at the Royal Academy, and it's absolutely heaving. The show of Turner's watercolours has only been open for a couple of days, but plenty of people seem to have decided to fit in a show along with their Christmas shopping.

I am standing in front of the great watercolour of Kilgarren Castle when, all at once, a daft couple nip in front of me and start inspecting it from a distance of about one inch. Their noses are practically against the glass.

Eventually, the man stops inspecting the brushwork, turns to his wife, and says "Almost Impressionist, isn't it?" She agrees, though, since they've only looked at it at the closest possible range, it's difficult to see how they can tell. I move on.

Five minutes later exactly the same thing happens; another gormless Bernard-and-Marjorie, up from Guildford for the day, walk straight in front of me and get down to some microscopic examination of the underdrawing. This time, she looks at the label's description of a watercolour-and-sgraffito view of Lake Albano, and asks her husband what "scratching-out" means. He hasn't the faintest idea. They're settling in for the duration, and I move on.

What the hell is going on? In front of every single picture is some idiot, who is examining the painting from the closest possible range. They can't all be painters, surely, who are examining the finest details of Turner's technique before dashing home to recreate it?

Has anyone ever told them that the way you look at a painting is not, as you might think, to stand back and see the effect of the whole, but to squeeze up close and breathe all over the glass? What they are getting out of it is hard to say, but I know what it's doing to the rest of us; making it impossible to look at anything properly. Cursing the vile cold that I caught in the Himalayas and which meant that I missed the press view of the show, I have to give the whole thing up as a bad job, and head off back home.

That whole phenomenon of getting intimate with pictures is a fairly new one. It's only really in the last 10 years that we've had to get used to people who insist on examining all the brushwork at such extremely close quarters.

Even at an Impressionist show, where the whole effect depends on viewing the painting from a certain distance, half the audience is indecently up close and personal, to the point that they could hardly tell you what the subject of the painting is.

If, at the Academy's late Monet show last year, you walked away to an appropriate distance, you could not see the painting at all, so surrounded was it by a lot of Guildford ants, poring over the painting as if it were a Mughal miniature. What the hell do they think they are doing? What conceivable pleasure are they getting out of it?

The answer, of course, is that art-lovers of this tragic variety are not really interested in art at all. They trundle from one newspaperapproved event to another, from Turner to Bostridge to Brendel, never wanting to do anything but show off at the time and boast about it afterwards.

The whole point of this grotesque behaviour is clearly to demonstrate to the rest of the world how sensitive and cultured they are; because only an incredible aesthete would get anything at all from the inspection of brushwork at this intimate level.

There's obviously quite a substantial enjoyment to be derived from this; at any rate, it clearly makes up for the fact that you haven't really looked at the paintings, or listened to the music, at all.

There's nothing more infuriating than some idiot preventing you from enjoying art or music, and when he is principally intent on demonstrating his own arty credentials, it is tempting to give way to rage.

There is the idiot who is only interested, at the Wigmore Hall, in showing how moved he was by the Schumann Fantasie, and starts applauding three bars too early.

There is the man who goes to Tristan and conducts the whole second act in his lap.

Worst of all, there is the ghastly, unspeakable monster who makes a point of laughing at the jokes in operas and in Shakespeare, when as everyone knows, they are not funny at all and never have been. It is very distracting for everyone else, and meant to be distracting, because to the publicly demonstrative aesthete, nothing is more important than the demonstration of his own taste, not even the work of art itself.

So do us all a favour. Instead of pretending to like painting, when you really all you want to do is to whip off your glasses and rub noses with a gouache, why not just shut up and stay at home?

If you only really want to show off, and talk about yourself all day long, then find some other pretext. The art galleries of London are quite crowded enough as it is. Please, give us all a break this Christmas, and go and be all sensitive and arty down the pub.

hensherp@dircon.co.uk