'Gay Art' by definition, to me, must needs imply that there is no mistaking it's meaning, and it is by this yardstick that I would measure if I were to need a reason. Irregardless of the artist, Mapplethorpe or other, I wouldn't think that a male or female nude portrait alone could signify anything. It is when they are become part of a greater context, other works that have a meaning which cannot be misinterpreted, that they may take on a more defining nature. I must say, this gay male, finds the human body to be incredibly beautiful and that means both the male and the female body. Sexual inclination, or identity, has nothing to do with it, the human body can be exquisite. I would be very pleased to have a fine nude of either sex on one of my walls.
But perhaps, I would prefer a fine, male nude.