From the (relatively obscure) Journal of Jules Renard: "You can do what you like: until a certain age--I don't know what--there is no pleasure in talking to a woman you cannot imagine as your mistress."

Ladies: this is true, at least in most cases. Sure, I talk to women I wouldn't sleep with, but when actually given a choice, and regardless of her marital status, I'm more likely to gravitate towards the women I'd sleep with. This isn't to say I'd actually suggest sleeping together. Fact: a man will glance at every woman and, either consciously or unconsciously, decide in fewer than three seconds whether or not he could have sex with her. In rare cases, his opinion could change--she might turn around, for example--but generally, our minds are made up: yea or nay.

If she's reading, however, she becomes fair game. And--beware, Boyfriends and Girlfriends Who Don't Read--the literati are much better in bed. Trust me.