POET, troubadour, rock star, call him what you will, there's no doubting that Bob Dylan casts an incredibly long shadow. Half man, half messiah, his autobiography Chronicles, published in 2004, proved he was also a convincing writer. His Bob Dylan Theme Time Radio Hour launched in the US in 2006 and now on the BBC has also established that he is a damn fine radio DJ.
Is there no end to his talents? Well, er, yes. A travelling exhibition, The Drawn Blank Series, currently at Edinburgh's City Art Centre, proves he really doesn't cut it as a visual artist.
I'll take a deep breath here and prepare to suffer the slings and arrows of outraged fans, because Dylan can draw on the most intense loyalty. This show comes larded with critical praise and wrapped in plaudits. There is a handsome catalogue with introductions by the poet laureate Andrew Motion. Of course, Motion is an avowed fan and a man who reputedly listens to Dylan every day. So it also comes with the critical credibility of an essay by Andrew Graham-Dixon, the avuncular one on the Culture Show.
Both Motion and Graham-Dixon fall into that category of cultured men in blue jeans. They are mainstream figures these days and it must have felt like a brilliant chance to get close to the counter-cultural hero of their youth. As for the City Art Centre, this is a shrewd travelling show for them to have taken, and I am sure it will prove to have been one of their most popular.
But, really, this exercise – organised in this country through Mayfair outfit The Halcyon Gallery – feels more than a little bit threadbare. Back in the period 1989 to 1992, Dylan spent an extensive time on the road touring in the United States, Europe and Asia. He whiled away some of the time, as he had been doing for decades, by making drawings of caf tables, empty hotel rooms, views from the window and a smattering of largely anonymous bare-breasted, bare-bottomed ladies who seem to find themselves quite accidentally sprawled on his hotel bed.
Persuaded by a German curator, he first put them on show some years later. I would love to have seen the original drawings, presented perhaps, as casually as they might have been created. In random sketchbooks or odd bits of paper, wrapped up with the detritus of the places they were made: hotels and cafes, trains and tour buses. Not very good perhaps, by the look of things here, but true to the spirit in which they were made.
This exhibition, though, is something else. Look carefully at these formally framed works of art produced in "an intense burst of creative concentration in 2007" and they are decidedly odd. They are not the paintings they appear to be. It emerges that beneath their awkward black outlines are computer scans of the original 17 year-old drawings. They've been daubed on top with what looks like watercolour and acrylic.
Once upon a time this kind of stuff might have been – generously – described as a hand-tinted print, now they call it "mixed-media on paper". For Graham-Dixon they are akin to "a fresh performance of an old song". To the rest of us the technique is more familiar as colouring in.
The same image is repeated endlessly in different colourways. Take Woman On A Bed, a fleshy lady in bra and pants. Here she is looking like a groupie in knickers and mood-lighting. Over there she looks like she is sunbathing on a Florida beach with a green bikini and a deep orange tan. Who are the Two Sisters, sprawled suggestively in mini-dress and studded bra? Why on earth has their hair been painted green? Why does the Woman In Red Lion Pub wear a different coloured frock in every frame?
All of this repetition would be fine if these were cool Warhol comments on the emptiness of the modern image. But the artistic styles Dylan uses, quoting figures like angsty Van Gogh, or urban voyeur Degas, are all designed to scream authenticity.
Many are authentically not very good, particularly the portraits where the sitters have identikit squashed faces and piranha jaw lines. The best images are on the more confident territory of home: an empty motel room, say, or a ludicrously luxurious New York apartment.
The irresistible urge when encountering the drawings of a famous person is the compulsion to perform amateur analysis. Perhaps the most overwhelming emotion evident in this show is not an often suggested melancholy but the genuine scent of fear. This is a man who can't trust his own hand to the extent, that he copies his old drawings and colours them in. He can't leave his hotel room. He rarely looks another human being straight in the eye but usually in the breasts or backside.
All of this would be just fine if it wasn't so ludicrously packaged. Alongside the show are a number of printed images for sale. The blurb calls them "limited edition graphics". They are on very nice paper, in editions of 295. They vary in price, but some will cost you more than 2,750 when framed.
A text panel prepared for the tour tries to explain why this is all okay: Picasso made prints too and his were inspired by Rembrandt. There we have it then: Rembrandt, Picasso, Dylan. As easy as 1,2,3. The problem with writing about a figure like Bob Dylan is that even surrounding him with such codswallop does nothing to dent the star aura. Lots of people will enjoy this show and feel that it gets them closer to the man.
In writing about it I feel like that lone heckler shouting out "Judas" in the Manchester Free Trade Hall back in 1966, when Dylan abandoned acoustic guitar for electric. Of course, back then Dylan was in the process of drifting away from folk and accidentally inventing modern rock music. These days, in some fields of endeavour, it seems he's just adrift.
• City Art Centre, Edinburgh until March 15