i think its okay as long as its VERY natural and used to enhance not mask their face. You should not be able to tell they are wearing make up like you usually can with girls....so playing around with colorful eyeshadows and stuff=no. I have a light sheer brown eyeshadow that you cant tell that there is any makeup there, but it does enhance the eye area discretely and thats the kind of thing I think is okay for men. Black nailpolish is the only nailpolish I have seen that looked "okay" for men. And I do think they should get their eyebrows done, get facials, and manicures. I cant stand out of control eyebrows and nasty nails. Unfotunatly most men think that caring for their appearence=gay...if only they knew why the gay men get all the chicks
But I admit sometimes It is a little scary to see guys a little to worried about their appearence, which is not uncommon in Tokyo. Espessially the ones who are more paranoid about their hair than a girl.