Perhaps the best way to capture this elusive quality at the center of Waits' oeuvre—this urge to tear a hole right through the center of the world's façade in order to make it a safe place for love and the domestic life—is to go back to the title track from Bad as Me. Here we have an absolutely typical Waitsian formula, where he turns "bad" on its head and redefines it as the relational glue holding together a passionate romance. "Bad" is what has put the lovers, individually, beyond the moral pale, but it is also precisely what brings them together.
I think a sense of sharing in Tom Waits' idea of "badness" is what draws a lot of his listeners to his music, and what keeps them coming back. I think it's what turns his bad voice—like a smoky scotch, its scratchiness is an acquired taste—into a "bad as me" voice that offers a kind of imaginary musical community to the legions who feel left behind in one way or another by the inexorable forward march of American civilization. His success in doing so shows that Waits has become a master of one of the oldest, and most central, of American cultural traditions.