I've often wondered about it myself but then it dawned on me. Have you seen alll those posers playing sweep solos and whatnot and then trying to make guitar faces? What are they vocalising? Bllll blllllll blllll Now think of a blues guitarist playing one note over and over and over again with expression. And he's making a face too, but it looks like a face that's been down so very damn long that it looks like up to me. The feelz, boys. Them blues.