The Nineties husband is a closet slob and his wife keeps his grubby little secrets because she thinks everyone else has the perfect partner. That is the sad conclusion of a recent survey I conducted on married life. Of the 80 questions, the one that received the most enthusiastic response from women was: 'Which of your partner's habits, characteristics or peculiarities do you like the least?'

At the top of the list came men who indulged in deliberate belching and farting. They were followed by men who picked their noses, ears, nails and eyes and ate or flicked the dirt; and men who left mess behind them - toenails in the lounge, trails of clothes, wet towels, dirty glasses and cups, overflowing ashtrays, a dirty lavatory. There were other complaints about smoking and poor personal hygiene, in particular feet and genitals, with the same socks and underpants worn day after day; and many more about men who obsessively channel-hop with an iron grip on the remote control. Was this behaviour too trivial to complain about, some of the women wondered; was it perhaps even amusing?

Of course, an accidental belch or fart can be funny, because it is a reminder that we are not always as much in control as we seem - but these women (more than half of the 300 I canvassed) were talking about deliberate behaviour, designed to antagonise, frustrate and disgust. Women do not find slobs funny; they are annoyed with themselves for being offended by slobbishness, and they are angry and hurt that men who can be a delight in company choose to be so repulsive behind closed doors. And it seems that women who suffer male slobbishness do not talk about it because they believe - quite mistakenly - that other women must have more considerate partners.

In answer to another question, women gave details of their partners' occupation, proving that slobbish behaviour is practised right across the board. But no male contributors complained of this sort of behaviour in women. Women are not known for being slobs. Generations of caring for other people means that women see comfort and cleanliness as simple common sense. Slobbishness disrupts comfort and makes work.

So why do men behave like slobs? One woman wrote that her husband's offensive behaviour was his way of 'trying to act big'. Being a slob does make a man bigger, because it increases the space he occupies. The slob claims his territory by strewing it with mess, like a dog leaving its mark. The slob also makes himself bigger by intruding on the space and the senses of others; his partner skirts round the smell, noise and dirt in which he sprawls; later she clears up after him. (A recent survey shows that housework is shared equally in only 1 per cent of homes).

Men are preoccupied with 'big', because it characterises their sexual identity. But a preoccupation with size invites comparison, and this causes anxiety and stress. According to Shere Hite, even men with the biggest penises worry that they aren't 'big enough'. Doubts about virility and bigness - in the real and in the metaphorical sense - are responsible for the fragility of the male ego.

It is clear from my survey that women like men who can accept self- doubt. The quality they most appreciate in men is emotional openness; a much-repeated statement was: 'I like a man who can cry.' A slob is a man who suppresses self-doubt. He 'acts big' to cover over his doubts with proof that he is big. The slob who offends his partner's sensibilities with his repulsive habits is the same man who will refuse to discuss emotional issues. He will withdraw from any situation that might force him to admit vulnerability.

Solitary slobbishness is often a sign of depression. A slob who lives alone in his mess is saying: 'I don't care for myself.' If there is a woman around, she will hear: 'Please care for me.' But when a man behaves like a slob in a shared home, it is an act of aggression. Here the message is quite clearly: 'I don't care for you.'

According to my survey, men often start to behave like slobs as a reaction to fatherhood. A man who is not committed to parenthood can behave with the jealousy of an elder child when a baby comes along to usurp his position, as he sees it, in his partner's affection. If a baby can exercise power over a woman with smells, noise and mess, a man can do it in a much bigger way. The slob relishes his 'revenge': his partner's irritation and distress.

Slobbishness works, in the short term. It oppresses the woman in a way that it shames her to speak of; and it makes the man feel big. But private undermining of women has a disastrous long-term effect on marriage: one third of the women in my survey had been living with slobs, and the relationship had ended.

And what was the habit, characteristic or peculiarity that most irritated men about the women who shared their lives? Though the survey was open to both sexes, only 10 per cent of the contributors were men, so perhaps no firm conclusions can be drawn. But several did mention excessive tidiness; and one said his wife cleaned the toilet first thing every morning - he wasn't allowed to use it and had to wait until he got to work.

'Inside Marriage' by Linda Sonntag is published by Mandarin at pounds 5.99.