Style. Tom Waits simply oozes style out of every pour. I don't know a single musician with more style than him. Style is of course a difficult thing to qualify let alone quantify. But he has it in spades. In fact, he has so much that he is a very polarizing artist. I think he's a genius and should thank Rex Martin for introducing me to his music back in the mid-90s.
As a side note, there is only one country in the world where I have heard Tom Waits being playing in a convenience store: +1 for Japan.
This is a live performance from the BBC program The Grey Whistle Test in 1977.