What, precisely, is ""bad sex""? Gathering contemporary writers from England, Ireland, Canada, Africa, and the US, Hoyland (Fathers & Sons, not reviewed) comes up with 21 quirky scenarios. Plots, for the most part credible, are more varied than one would imagine. The volume itself is masterfully orchestrated. Early stories are calm and tender, focusing on relationships in which sex plays a small part. Lisa Appignanesi's ""Beast"" captures the unique point of view of a husband whose feminist wife has just published a book about masturbation. In ""Strange Attractors"" Jane DeLynn tediously but perceptively chronicles the way people keep toeholds on dying relationships: Her narrator doesn't like drugs or alcohol but uses them ""for fear that we would no longer be able to converse at all if our bodies were not being affected by the same constituency of chemicals."" As the collection progresses, the texts gradually become more explicit. Some can be discreet, if not charming -- Victor Headley's ""Christmas Present,"" for instance, whose narrator, embroiled in a relationship built solely on sex, sees himself as a worthless stud. But in the stories that follow, the intensity increases, S&M imagery appears, hints of murder surface. (It's impossible to read Ian Breakwell's pseudo-diary, ""Fade To Black,"" without cringing.) Then, just when you want to toss this book away, the stories become gentle again -- but now they are anything but innocent and contain some wonderful humorous touches. The married lover in Catherine Hiller's ""Some Rules About Adultery"" carefully stages three afternoons of bad sex in order to end a two-year affair. Mary Scott's ""D.I.Y."" portrays a promiscuous woman, wanting a break from men, who goes on a ""women only"" tour, only to discover her trip-mates are all paired off. In perfect closure, the protagonist of Molly Brown's ""Choosing the Incubus"" finds her human lover pales beside her demonic nightly visitor. The title might be a turn-off, but the texts themselves are surprisingly enjoyable.