For half a century, rock 'n' roll has been as sex-obsessed as a teenage boy -- or a stressed-out politician. Strangely, though, rock becomes prudish when love requires the transfer of cash. Still, hustlers and ladies of the night have occasionally caused tunesmiths to take at least pen in hand. Sometimes these sex professionals cause the ruin of a doe-eyed client. Sometimes they're the ones who are ruined. This gives call for us bloggers, in the world's newest profession, to present 20 songs about the world's oldest.

'Bad Girls' (1979)
-- Donna Summer

Many songs of the disco era embraced hookers, and Donna Summer rode this streetwalking cheetah all the way to No. 1. It's full of judgment at the outset, as Summer decides "bad girls" = "sad girls" because they really just wanna be stars. But by the song's final verse, Summer has found her own inner bad girl, sidling up to a potential john offering some quality time.