And, no, I don't mean that song by Marilyn Manson. I mean folks whom I've seen where it was not possible at all for me to guess their sex and as a result, they were beautiful to me.
So far, there have been at least 2 that I can think of off-hand.
I used to see a person at a bus stop in San Francisco in the early '90's. They were slight of build, tall, had short hair, and a somewhat angular jaw. Their baggy clothes hid any curves or suggestion of such. Something about the shape of the face made me think bio-female but I couldn't be certain.
The second was someone I used to see jogging while I was on my way to work in Mountain View a few years ago. This person was bald, somewhat roly-poly, and their chest would bounce as they ran. This could have been loose pectoral muscles or breasts; I couldn't tell. The overall body shape made me think bio-male, but again I couldn't be certain.
Then in between, in the late '90's, I used to see a person at a CalTrain station here in San Mateo. This person always dressed in long flowing black clothes. Sometimes, it was an ankle-length dress, sometimes it would be a simple black shirt/blouse and clearly women's slacks, and always black flats. Their thick dark brown hair was a bit more than shoulder length, and the mustache and goatee were quite full. This suggested bio-male to me, and also suggested that this particular person was extremely brave.
Reflecting on these beautiful people, I wonder why I had been trying to guess their sex. Really, what does it matter? I think it must be partially instinctual to try to classify people, though I don't understand why. I'm still trying to unlearn this reflex.