As far as I can establish, no experimental psychologist has ever conducted research into the mental and emotional states of self-help authors, motivational speakers and life coaches. Somebody should. I'm only half-joking: the results may confirm, or put to rest, the nagging suspicion you get from too many books on finding happiness or success that their authors have found neither for themselves. As with the father in Little Miss Sunshine - driven to the edge of breakdown by his failure to find a publisher for his nine-step success programme, Refuse To Lose - one detects the whiff of desperation wafting from self-styled experts who act upbeat at book-signings, then return to their motels to cry into their pillows.

This is a gross generalisation, but the issue is real: in a culture in which advice on how to live spews from every bookshop, magazine and TV channel, how much does it matter what source it's coming from? It wouldn't matter if it just meant avoiding lantern-jawed conmen, or Daily Mail articles promising "a new you in 24 hours" (you, too, can achieve peace of mind like Melanie Phillips's!). But even the authentically wise seem plagued with problems. How are you supposed to respond to learning that Scott Peck, whose The Road Less Travelled counsels self-discipline and deferred gratification, was serially unfaithful to his wife, who then divorced him? "There is frequently something pathetic," he wrote, "about the individual who has failed to build his or her family into a loving unit, yet restlessly searches for loving relationships outside the family." Indeed - and Peck is hardly unique.

For some, this is the killer blow: proof that everyone hawking advice is cynically motivated. Then again, wouldn't you rather seek guidance on dealing with difficulties from someone who'd actually dealt with them? "When confronted by a human being who impresses us as truly great," wrote Freud's biographer, Lou Andreas-Salomé, "should we not be moved rather than chilled by the knowledge that he might have attained his greatness only through his frailties?" Everyone's imperfect, leading us to the awkward conclusion that the only people worth listening to are those who did not just face battles in the past (that's in every charlatan's clichéd life story) but who don't always follow their own advice.

This is a paradox, but it needn't mean all advice is worthless. The problem, surely, isn't with self-help, but with attaching ourselves to gurus and believing all they say: the opposite of self-help. The best advice throws you back on yourself, leaving you in no doubt that the decision to pursue any course of action is always only your own, and the best advisers shun the role of guru. Here's psychotherapist Sheldon Kopp: "It is as if I stand in the doorway of my office, waiting. The patient enters and takes a lunge at me, a desperate attempt to pull me into the fantasy of taking care of him. I step aside. The patient falls to the floor, disappointed and bewildered. Now he has a chance to get up and try something new... He may transform... his bid for safety into a reaching out for adventure."

oliver.burkeman@theguardian.com