At least it's not Jordan ... Comedian and novelist Stephen Fry looks out over PG Wodehouse's heritage 'blue plaque'. Photograph: Ian West/PA

It's a depressingly familiar sight in bookstores nowadays: shiny tomes "written" by footballers, pop stars and reality TV types crowding the display stands. People who have no proven literary talent, cashing in on their fame while they can.

"We seem to live in a time when some publishers will trot out any idiot who's had their 15 seconds of fame and get them to write about their lives - or more likely grunt at someone who will then write about the couple of years of their life worth knowing about," one disgruntled publisher has observed. "The problem is that there's an insatiable appetite for this crap too."

But it's not reality TV stars or footballers that account for the highest crossover to the bookshelves. It's professional comedians - and they're not just writing biographies, they're writing "serious" (or semi-serious) fiction. Mark Watson's A Light Hearted Look at Murder is published this month, and veteran household names have long been at it. Stephen Fry has churned out four novels and a host of non-fiction titles, Jo Brand has written two novels, and Harry Hill has penned a number of children's stories, as well as a comic novel for adults.

From a publisher's point of view, backing a comedian makes sense. Why gamble with an unknown, with all the attendant pressures of breaking them out and committing to the long haul of their career, when you can cash in on an established name? David Baddiel, Meera Syal and Alexei Sayle's novels have been generally well received. And they all had the decency to write the things themselves.

In many ways, the skills honed by comedians are not so different from those of a writer. Comics make their living observing the minutiae of life, playing with words, and devising routines much as a writer crafts a narrative - with endless edits, improvements and revisions.

And comedians can draw on valuable experience from live audiences, whereas many novelists never get a chance to test what strikes a chord with people. No wonder then that AL Kennedy performs as a stand-up when she's not writing award-winning fiction.

Indeed, with all these natural advantages, perhaps the question we should be asking is not why so many comedians get published, but why so many of their novels end up being so bad? The irrepressible Ben Elton is responsible for more than a dozen (and the title of his 2006 novel Chart Throb pretty much sums up his oeuvre), and even the prodigiously talented Stewart Lee's novel, The Perfect Fool, was bafflingly mediocre.

Perhaps with Elton it's a case of intellectual snobbery. Whatever highbrow critics might say about him, his books do sell in vast quantities.

But in general, it seems that publishers are sometimes so eager to save their marketing and publicity departments work, they give little thought to (or simply don't care) what goes between the stardust-sprinkled covers.

Dave Gorman has said that "all sorts of unpleasantness could have been avoided if other people had told me not to [write a novel]. Instead, they took me seriously. Meetings were set up, deals were done and a novel was commissioned. To make matters worse, a publisher even gave me a chunk of money as an advance on the project. This was an exceedingly stupid thing to do."

Success often deludes people into thinking they are capable of doing things they are not - or as Alexei Sayle put it, success offers you the chance to "disappear up your own arse". This may be true about some comedians. But I'd still prefer to take my chances with someone who's been entertaining people for 20 years over some ghost writer purporting to be a 23-year-old footballer.