Bisexuality

[Rubang B]

That's a very good point Hydralisk, but while some people might not be a perfect 3 at any given time according to your theory, many people's sexualities may shift and evolve during their lifetime. They might be a 2.5 for a couple years and then a 3.5 for a couple years. Not all bisexuals go "back and forth" as fast as most people expect. They might be in a 5 year relationship with a woman and then in a 5 year relationship with a man right afterwards. Or they might go to a club looking for a hot guy on Friday and then go to another club looking for a hot girl on Saturday. Or maybe they want to bring home one of each? Teehee...

Your personal pleasure criteria is also a great point. Some people are actually more physically attracted to one sex or gender while more emotionally/romantically attracted to the other sex or gender. I even had an ex-girlfriend who was only physically attracted to the female body but only dated, fell in love with, and became romantically involved with men. Where do you put somebody like that on the Kinsey Scale? Do you pay more attention to their sexual fantasies or their actual sex life or who they fall in love with? I think perfect 3's do exist in all 3 of these categories, but they could easily be just as rare as a pure 0 or a pure 6.