My housemate has on several occasions described lines of poetry (or prose sentences) as "sexy". I have always wondered what made sentences sexy rather than merely well-written: must you envy the sentence? Must you wish you had written the sentence or must the sentence be endlessly compelling? To my delight, I came across a reference to "sexy sentences" in Barthes by Barthes:

Different from secondary sexuality, the sexiness of a body (which is not its beauty) inheres in the fact that it is possible to discern (to fantasize) in it the erotic practice to which one subjects it in thought (I conceive of this particular practice, specifically, and of no other). Similarly, distinguished within the text, one might say that there are sexy sentences: disturbing by their very isolation, as if they possessed the promise which is made to us, the readers, by a linguistic practice, as if we were to seek them out by virtue of a pleasure which knows what it wants.