How many books can one man recommend? I sometimes feel that my name is on the cover of more books than I've actually written myself, which is worrying. I've endorsed children's authors as diverse as Suzanne Collins, Meg Rosoff, Simon Mayo and the late, great Robert Cormier. I found the historian, Nicholas Rankin, to be "completely delightful", and the poet, Roger McGough, "wise, funny and sad". The thriller writer, Stephen Leather, delivered in my opinion, "a wicked read" although I notice I've been bumped off the front cover of the latest edition by James Herbert ("another great thriller with a devilish twist"), which I do find slightly hurtful. I even turned up on a self-help book I hadn't read – the publishers took my name and helped themselves.

Authors promoting authors on book jackets is so widespread now that few books appear without them, a phenomenon gleefully mocked by Private Eye's Backscratcher column, which is quick to point out where favours are being called in. There are three ways in which I find myself on other peoples' covers.

The first is perfectly legitimate. I write a positive review for a newspaper and the publishers quote from it. Frank Cottrell Boyce wrote kindly about me in this very newspaper about a month ago, and as it happened his piece coincided with a new edition of my paperbacks. His words are already plastered over the covers and I doubt my publishers asked if he minded. That said, I decided to read his last book, Cosmic, out of a sense of gratitude and I can say with hand on heart that Frank is one of the funniest and most engaging writers on the planet – and I'm willing to bet you'll read that again on a cover one day.

Of course, reviews are open to interpretation – or re-interpretation. I was a touch surprised to find myself extolling the virtues of Jeffrey Archer's latest bestseller, Sins of the Father, last month because what I remembered writing was a slightly critical profile of the great man. But careful editing had turned me into his most craven admirer. I didn't mind though. I enjoy his work and you could say that, in the manner of one of his own stories, I had been hoisted with my own petard.

The second fast route to front cover fame is the summer and Christmas round-ups, which appear in most serious newspapers and which are a gift to publicists. This is where authors write about what they've been reading, and it's something I'm always very happy to do. After all, everyone enjoys recommending a book and I even get paid (usually a bottle of not very good champagne). But the question is, am I morally flawed if I promote books written by my friends? My choices last year were One on One by Craig Brown and The Thread by Victoria Hislop and as it happens I know them both personally. Well, in all honesty, I loved both the books and they were widely praised elsewhere but even so I did feel a twinge of conscience. Funny, now I think about it, that the Eye didn't pick up the Hislop connection.

But the most difficult approach comes from people who know me slightly or who work with me in some way – often being published for the first time. Will I read their manuscript and offer something for the cover? I have to say, I dread this. It's as if I'm walking into an emotional minefield. You might think I'm being churlish. But it seems to me that the request comes with so many suppositions. 1) That I have time to read the book 2) that I will actually like it 3) that if I don't like it I will pretend otherwise because I don't want to hurt their feelings and anyway what does it matter if I lie to the public, it's only a bit of blurb – and 4) that my name will help with sales anyway..

I do wonder just how much a name is worth. Have sales of Meg Rosoff's There Is No Dog soared because I said it was a work of genius? Would Alex Rider fans rush out and join the army of kids who love Robert Muchamore's Cherub books if I recommended them? They're probably reading them already. In fact, in the world of book promotion, there can be an inverse effect to the one intended. The Hunger Games has so far sold 36.5 million copies and I've been on the cover! Isn't that actually 36.5 million advertisements for me?

At the end of the day, author endorsements are probably of minimal value. Does anyone really believe them? Browsing through the crime section of my local Waterstones, I get a true sense of conspiracy. Harlan Coben praises Michael Connelly. Michael Connelly loves Jeff Abbott ("A hell of a page-turner"). Jeff Abbott is praised by Lee Child who is admired by Stephen King and by Jeffrey Deaver. There's Ian Rankin plugging Val McDermid who's a fan of Harlan Coben… or maybe it's the other way round. I'm not saying any of these authors are insincere. But the overall impression is simply that big writers like big writers and my reaction is – so what? Tell us something we don't know.