Tom Sutcliffe: It's hard to be a critic when you love something

Saving grace: Paul Simon's voice isn't 'faultless', but his capacity as an emotional performer is as strong as ever (Getty Images)

One of the commonest of all critical vices is reviewing the work you wish you'd experienced instead of the one you actually did. But it struck me this week that there are actually two versions of this vice – opposed to each other by almost 180 degrees.

The more common form of the flaw – wearily familiar to writers and film-makers – is to review what you think the work should have been rather than what its creator actually intended. And, almost without exception, this is bad news for the creator in question, since a sustaining thread of disappointment runs through the resulting piece. The critic helpfully points out how much better the book or film would have been if he or she had written it, while ignoring the fact that it was never what the author had in mind in the first place.

The other version is very unlikely to make artists complain, but is, I suspect, far commoner. And it consists of reviewing the performance you hoped you might get before you actually turned up... or, to put it another way, of reviewing the performance you'd love to say you'd been at. This too involves critical inaccuracy but it's driven, in this case, by an admiration for the artist in question rather than an indifference to his or her intentions. The review I'm thinking about in this respect was one that followed Paul Simon's Graceland concert in Hyde Park the other night and which, in the course of a 360-degree rave, described Simon's voice as "faultless".

I went to that concert, very much enjoyed it, and found myself in tears at at least two points – one of them being a stunning solo performance of "The Sound of Silence", backed only by acoustic guitar and a beautiful London twilight. But I don't think I'd have described Simon's voice as "faultless". He's 70 years old now and it isn't what it was... but that hardly mattered. Its frailties were integrally part of the emotional content of the show. That critic, it seemed to me, wasn't reviewing what he'd actually heard, but what he wanted – in his admiration for a great singer-songwriter – to be true. His was an inaccuracy of love, not condescension.

I suspect that the second kind of wishfulness is the one we're most prone to as consumers of art. We like to feel that we've invested our emotions (and our cash) in something worthwhile and we're disinclined to confront any evidence to the contrary – even when that evidence doesn't really amount to a contradiction at all. So we tell ourselves a little white lie about what we've seen. The best critics though – and the best readers and watchers too – don't tell lies at all.