Critics don't have it good at the best of times. This past week, however, the knives really were out for them. At the book launch for James Runcie's Canvey Island, rather thrillingly held on a Chelsea houseboat belonging to Alexandra Pringle, editor-in-chief at Bloomsbury, Runcie mentioned that his novel had been reviewed by the Times - rather unsatisfactorily. "The critic highlighted my treatment of Mrs Thatcher. But I don't mention Thatcher once in the book," said Runcie, whose novel is set in England from 1953 to the present day. "The book's press release from Bloomsbury does. So my book has been ignored by the critic who has, instead, reviewed the press release."

Meanwhile theatre critics are getting a drubbing with the help of R Cubed, a vicious e-mail circular by Ian Senior. It aims to do unto theatre critics (or "the Cretinue", as Senior calls them) as they do unto others. The lawyer Marcel Berlins recently devoted his Guardian column to a campaign for the "two-visit theatre review", particularly for plays that have been mauled by the critics. His reasoning is thus: it's unfair if all the critics see a show on the same night and rubbish it. Press night might have been an off night. So all the critics should go back to the show and see if it's still rubbish. That would be fair.

Berlins uses the dire Resurrection Blues at the Old Vic as an example, because apparently it got a bit better after press night. But not much better, because it has now been taken off. Which means either that Arthur Miller's last shot was fundamentally a bad play, or that the dim theatregoing audience has been gulled by the nasty critics. One suspects this is Berlin's viewpoint. But why, then, are Lloyd Webber musicals successful? They are usually slammed by the critics, but have an annoying tendency (annoying to critics, that is) to stay in the West End and play to full houses for years. Audiences know what they like, often regardless of what the critics say.

Anyway, it's a bonkers idea. "Berlins is a lawyer. Does he think judges should view cases twice if they decide to bang someone up?" asks the Variety critic David Benedict, who bridles at the suggestion that Resurrection Blues just had an off night. "Maximilian Schell, who starred, had a memory problem and was reliant upon an earpiece feeding him the lines," he says drily.

Quite apart from this, there is the practical issue. There are more than a hundred reviewable theatres in London. Most critics are out every night as it is. How could they possibly manage to see shows twice? Frankly, the very idea of sitting through The Royal Hunt of the Sun again is a hideous one . . . unless it was a school production, and one of my children was starring in it. Even then, I might have to take a rain check after the interval.

Besides, the very idea of revisiting a show in order to judge it runs counter to the singular character of live drama. A play is going on before your eyes. It cannot be rerun, slowed down, or paused. You can, of course, go to see it again - the very next night, if you wish (barring Mike Read's musical on Oscar Wilde, which closed after just one performance). But most audiences tend to buy tickets for a show and assume they will get the whole experience in a single night . . . unless they are Phantom of the Opera nuts who have seen the play umpteen times. And then they can do all the double or triple reviewing that Berlins wants.