There's been a wonderful furore over whether or not Alastair Macaulay, dance critic of the New York Times, should have said that the ballerina playing the Sugar Plum Fairy looked as though she'd had one sugar plum too many.

It boils down to whether or not you should, as a critic, refrain from unkind remarks in print about what a performer looks like. This seems to me the most abjectly silly nonsense that ever I have heard.

A performer gets on a stage and performs. With heart, mind and body. All three are fair game for critics, and being rude or not simply doesn't come into it. What an actor, or a dancer, looks like is what critics write about.

You could fairly say, for instance, that Derek Jacobi's eyes are too close together, or his features too tight, to allow him the full facial and physical apparatus needed for a great tragic performance.

Similarly, I used to think that Harriet Walter's voice was too small; in the theatre, it sounds as if comes from her throat, not her diaphragm, and is therefore less rich, say, than Judi Dench's.

These comments do not mean that either Jacobi or Walter are not exceptionally fine actors. Jacobi's Peer Gynt, and Walter's Cleopatra, were as good as any I've seen. But the idea that a critic discusses a performance without reference to physical attributes and appearance -- good, bad, or ugly -- is patently absurd.

Another recent example: I happen to think that Michael Xavier is too tall for his role in Love Story. He sings it beautifully, and he's a good actor. But he towers over Emma Williams in an awkward way, and he doesn't carry the charismatic sexual punch, certainly of Ryan O'Neal in the movie, nor of what one hears about him as a character from the other people on the stage.
Yet again: Roger Allam was in many ways the exemplary Falstaff of recent years, and his was a fantastically well spoken and beautifully considered performance in the Globe this summer.

But he wasn't fat enough (Falstaff rarely is). The main thing about Falstaff is not his self-delusion, nor his cowardice, nor his brilliancy of wit, nor even his padded girth; the main thing about him is his grossness, his disgusting, earth-larding, barrage ballooon, physically repellent and gargantuan size and smelliness.

In the case of the Sugar Plump Fairy, Jenifer Ringer, it was said on a BBC Today programme discussion that she has a history of an eating disorder. If Macaulay knew this, as he must have, this renders his fairly innocent remark slightly ungallant. But being a critic has nothing to with gallantry. You're a critic, for heaven's sake.

There was a brisk attack by A A Gill on the Cambridge classicist Mary Beard in the Sunday Times yesterday. Beard had had the temerity to present a close look at the past in Pompeii without taking a close look at herself in the mirror before stepping in front of a camera.

The hair was a disaster, said Gill, the outfit an embarrassment. Beard, who's a lovely woman, had not gone to the trouble of giving herself a dishonest make-over. As it happens, I like her the way she is, and the way she looks.

But Gill is perfectly entitled, as a critic, to make the point that "if you are going to invite yourself into the front rooms of the living, then you need to make an effort, or at the very least take some advice."

This is a valid critical comment, still leaving plenty of room for people to disagree with it. What amuses me is that Beard herself is quite a stickler for appearance in other people.

Years ago I complained about an actress sporting hairy armpits as a goddess in Pericles. Beard, suitably enough, came to my defence in the subsequent uproar by saying that such a figure would only ever have been represented entirely smooth-skinned in antiquity.

Of course, and again, you are still entitled to entertain a modern interpretation on this point; I was being inflammatory in the days when you were still allowed to be so (and thank heavens, these pinched and politically correct days, for Gill). 

But I like to think of Beard advocating shaved armpits in the temple at all times, even if we weren't allowed to check how rigorously she applied this dictum to herself as she wandered eccentrically around the ruins of Pompeii.

"My brother Esau," said Alan Bennett in Beyond the Fringe, "is an hairy man. But I...I am a smooth man." When it comes to evaluating performances, we must be allowed to register the difference.