Pop quiz: What do you really know about Michael Bolton? Here's what I've got: long, curly blond hair (or at least at one time); was once engaged to actress Nicollette Sheridan (that's over); and he — with the hard-rock band he used to be in — once toured with Ozzy Osbourne. O.K., that last one was a new discovery, well worth knowing. The moral of this story is that Michael Bolton is a tad obscure, and no one seems to know what kind of music he sings. Adult contemporary? What the hell is that, anyway?