It was no surprise to read in SID that someone would describe Michael Jackson as sexually ambiguous. Mercer states the obvious when he addresses MJ's androgynous appearance, mannerisms, and mystique surrounding his overall image. But I have to admit the term "racial ambiguity" was new to me. At first I thought it meant that we couldn't tell if he was black or white, but that was a superficial interpretation. I don't even think it means that we're supposed to wonder if Michael Jackson is white or black. I think it means MJ's image is not 100% or even 50% a reflection of a particular race or culture. With his music, dance, and image, MJ is able to embody, embrace, and reflect the races and cultures who embrace him.
I watched and listened to MJ all the time when I was a kid growing up in the 80s and 90s, but I never once wondered "is that a boy or a girl?" or even "is that a black man or a white man?" He was simply his own category of human. Michael Jackson.
In a way, I think MJ transcended a lot of boundaries with his ambiguity, which is why he had such mass appeal. He is a sex symbol without muscles, but his physical ability drops jaws. No one really knew what was going on with his skin/face, but the voice that came out of his mouth was the same no matter what he looked like.
As eager as our culture is to slap labels on people (male/female, black/white, gay/straight, whatever) no label seems to stick to Michael Jackson. Such a wide audience can find a piece of themselves in him, that I might be so bold as to argue that he is one of the most 'related to' artists of all time.
It's possible that in all this ambiguity, MJ himself couldn't self identify except as a private and public version of himself. He will always be an enigmatic pop culture icon, even if we can't quite put a finger on exactly what/who he is.