Books: And so to bed - with a headache: The A-Z of sex? Joan Smith finds the year's 'erotic' books lower the spirits

WHY IS IT that my heart sinks every time I look at the pile of sex books sitting tidily on my desk? Virtually the whole of human erotic activity is represented here - and it's depressing.

To some extent it's a matter of taste. Good sex means different things to different people, and I do not look forward to trawling my way through pages of sub-Lawrentian humpings. This is not to argue thatit's impossible to write well about sex, but I had a well-founded suspicion that the Bloomsbury Guide to Erotic Literature (ed Jane Mills, pounds 19.99) would contain few gems, alongside reams of stuff from authors whose erotic effects are on a par with small children showing off their genitals. This turns out to be especially true of the 20th-century section of the book, which rounds up all the usual suspects - Hubert Selby Jnr, Georges Bataille, William Burroughs, Henry Miller - and reveals a disturbing obsession with sex and violence. Mills argues that the 'association between Eros and Thanatos' stretches back to Homer, but there is a difference between using death as a metaphor for sexual exhaustion and the graphic violence which is a consistent feature of these writers' work. It's true that a nasty passage of flagellation and blood-letting a trois from Apollinaire stands in a tradition of libertinism going back to the 18th century, but I would like to know Mills's thoughts as to why this type of infantile exhibitionism has emerged as a popular theme in our own century.

Another way of approaching the erotic is to concentrate on writers and movements rather than reproducing the literature itself. This is Harriett Gilbert's method in The Sexual Imagination from Acker to Zola (subtitled 'A Feminist Companion'; Cape pounds 14.99), yet it is not without its own problems. Gilbert claims that the book's 350 entries, 'by an international team of feminist authorities on literature, art, religion, sexology, psychology, philosophy, sexual politics and more, are actually miniature essays': what they tend to consist of is an uneasy blend of fact and opinion.

There are puzzling omissions - no entry for Madonna, for example, who surely poses a challenge to the sexual imagination - and some utopian predictions. On misogyny, for example, Gilbert suggests optimistically that 'as we dismantle the practical patriarchal structures, so the misogynous, poisonous plant that clings to them . . . will collapse and expire of malnutrition'. If there is a single sentence which sums up the dangers inherent in a synoptic project of this kind, it is this startling pronouncement on Wuthering Heights: 'Death, Bronte is saying, is sexy.'

Richard Davenport-Hines archly presents himself as the King of Shreds and Patches, the character who used to represent vice in mystery plays, in his introduction to Vice: An Anthology (Hamish Hamilton pounds 17.99). 'A celebratory tone has been my aim,' he announces, casting his net wide enough to include not just seduction and adultery (whose status as a 'cheerful' vice is, I think, open to question) but dancing and shopping. The book contains some interesting but not obviously related pieces, including a touching account by James Lees-Milne of a love affair conducted entirely by telephone, with no indication of whether the extract is autobiographical or fiction. Publication dates are given only for the least-known pieces; authors' dates have to be looked up in the index.

Dawn Sova's Encyclopedia of Mistresses: An Under-the-Covers Look at the 'Other Women' of History's Most Influential Men (Robson pounds 16.95) is as silly and sentimental as it sounds. Sova has nothing new to say about the women who appear, alphabetically, in her book, and I can't imagine who needs to be told that 'Marilyn Monroe excited desire in every man she met' or that Mary Wollstonecraft 'recovered her self-esteem and decided to meet with radical philosopher William Godwin'.

I've left one of the best till last: Bad Sex (ed John Hoyland, Serpent's Tail pounds 7.99). Here, semi-erections, unconsummated longings and horrible one- night stands abound. Against all expectations, this collection of stories is the least depressing of all these books; it's nice to be reminded occasionally that not every sexual act results in a spouting, pushing, ecstatic orgasm.