"Real" Bisexuality

So, I have thought alot about the common idea of "real" bisexuality, and who is or isn't really bisexual. When that damn Katy Perry song came out, I was frustrated as shit. My queer friends and I complained about "party lesbians" as we called them. Girls that only make out with other girls for male attention. Recently I've come to re-think my position about the "sometimes lesbian" (although not necessarily the action of wearing ANY kind of sexuality only to titillate men; more on this later in the post).