If you want to know the vulnerabilities of your house — which window latches are loose, which locks won't hold, every crack, fissure and loose brick — the best person to show you is a burglar. If you want to know the vulnerabilities of your self, you need a con man. A con man can find his way into all the areas of your life that you have tried to keep secure: everything hidden, hopeful, anxious and uncertain; all those secret desires and doubts. Conning is the cruellest art. Like a negative form of therapy, it recognises and exploits the concealed truths that we most shrink from.

Recently, John Keady, a serial conman, was jailed for five years and three months for swindling thousands from women he met on internet dating sites. These women were usually professionals in their thirties and forties.

Smooth criminal

Keady posed as a wealthy businessman; he would go through the charade of house-hunting with the women he met, taking them to look at properties worth millions; he said he had homes in France, Scotland and Cornwall; he told them he was a world-class kayaker, he dated several women at once, stole their credit cards and borrowed money he never returned.

He stole £10,000 (Dh53,878) from his adoptive mother. He even tried to con the judge, claiming he was a decorated lifeboat hero when he had been out on a few routine rescues. He created his own version of reality, into which he lured his victims. On one of the sites he called himself "Icarus Boy".

He's had his wings burnt — for the time being. As Judge Christopher Elwyn said: "Lies are woven in the fabric of his being." Police took evidence from eight of his victims but they believe that there may be many more who are too embarrassed to come forward. For what this sorry tale demonstrates is the extraordinary ability of the con man to gain the trust of his victims and the touching emotional vulnerability of the person who is conned.

When people describe what makes a good teacher, therapist or friend, they often talk about the ability to recognise the individual, and to make them feel special and cherished. To those who wanted security, Keady was rich; to those who wanted adventure, he was an intrepid traveller. On one occasion, Keady acted out shocked distress in front of one of his dates when he apparently discovered that his friends were trapped in the Himalayas and needed rescuing. She duly coughed up £11,000 (Dh59,289).

Tearful scam

I once handed over £22.90 (Dh123) to a young man with wild hair and tears streaming down his face who claimed that his daughter had just been run over and was fighting for her life in Stoke Mandeville Hospital. He had locked himself out of his flat and didn't have any money to get the train to be with her. I know it was a con because he extracted the same amount of money from my friend, and then returned a few weeks later to my door, still wild and weeping. He must have earned a lot of money, by knowing exactly which story to use. Who would deny a grieving father the last chance to be with his dying child? Only someone as calculating and emotionless as himself.

There's a brutal quality to the most skilled conman or woman. They understand feeling, without possessing it. Keady is in a long line of persuaders who make their victims feel special. It's hard to believe that Keady acted only out of financial motives — the deceit is so scrupulous and all-encompassing that there's a psychopathic and grandiose desire to control and humiliate.

Trashing trust

Keady stole money from his victims but he also stole trust. They were looking for affection and he took that need and trashed it, and in so doing made them feel ashamed. But what are they ashamed of? Being stung, being gullible, being publicly exposed, having their secret needs recognised and abused — in other words, being part of the messy, optimistic, questing human race, in need of love, wanting to trust.

There are many websites that give you tips to avoid being conned. They include advice such as to check stories, to be perpetually suspicious and cautious, to recognise the "signs" of the conner. And what are these signs, but ones that make the world a happier place to be: interest in you, affection, generosity. There will always be psychological tricksters such as Keady, and there will always be victims like the women he abused, because trust is what binds us together. The person who could never be conned is the one who could never be hurt and never be loved.