I dated a guy once who wore makeup...and I didn't even know it until 8 months into it when I found said makeup in his medicine cabinet. At first, I reacted negatively. "Throw that shit away. What are you, a girl? Some kind of prissy little bitch?!?!?"
But then I questioned my reaction - why was I afraid of a man wearing makeup? What did his wearing makeup say about me? Did it threaten me somehow? He was the one wearing it, not me, so why did I feel it was some reflection of me?
Of what was I afraid?
This led to more internal questions about masculinity, femininity, and how we embody these things. I read some Paglia, some Focault, some Susie Bright, a several others including this amazing book on the taboo of obstacles and how we use them to enhance attraction. Wish I could remember that book, it was written by a gay psychologist in the early 90s.
My answers (both realized and found) led me on the path to where I am today in terms of understanding gender, gender identity, gender expression and more in relation to greater social mores and norms. Where I have little patience for the masc/femme debate that's often quite deeply rooted in ignorance and fear.
That said, I wouldn't go to dinner with an "Alice Cooper" - not because he's wearing makeup, but because his likely tastes in music would make road trips IMPOSSIBLE!