Addressing the first issue (that is a far as I got) my familiarity is with the gay community here in San Francisco, and there are plenty of examples of cognitive dissonance that still emerge.
One is (or at least used to be) the common Fleet Week occurrence, which are sailors who are definitely not gay, but they do love them a some bear cock (or required to be heterosexual [http://tvtropes.org/pmwiki/pmwiki.php/Main/TwentyBearAsses], but there's still some stigma so that it still happens.
It also happens fairly regularly with civilian men who, for one reason or another (say, they're married) don't want to admit that they like a bit of the pink mayonnaise cannon [http://www.fiftyshadesgenerator.com/] now and again. Usually, the more they have to lose, the more discreet they have to be.
On the flip side, I've had a couple of girlfriends who were adamantly lesbian even when we were sexually active and sexually exclusive. Part of that is this phenomenon is that lesbian is a community (and a somewhat conformist one) here in San Francisco. Bisexuality has stigma much like gay does in the conservative mainstream. Maybe more so.
I think it usually comes to that: people identify more with the community they're in rather than who they like to fuck, so that even as we reduce homophobia, people will still identify as gay, straight, lesbian, whatever. Very similarly, I identify as BDSM even though my sexual proclivities run fairly vanilla, but I was raised (that is sexualized as a young adult) in the BDSM community. I know my way around negotiation, safewords, limits and boundaries, munches, parties, floggers, toys and so on, and so those are the people with whom I identify, whether or not I invoke restraints and clamps in my loveplay.
Regarding the specific transsexual / futanari fetish that seems to go around quite a bit, Dan Savage hypothesizes it's a way that some of us express our fascination with penises that are not ours, yet find the whole masculine shape / energy / whathaveyou difficult to sexualize, so (fantasy being a malleable thing) we attach oversized cocks to voluptuous women (or in some more interesting cases, other things). One wonders if this is the what caused glory holes to be invented. Pre-op (or partial-op) trans are, in this light, a real-world opportunity to actualize that fetish.
But what this means is that just because you appreciate some futa doesn't mean you're particularly high-ranking on the one drop rule [https://en.wikipedia.org/wiki/Kinsey_scale]. Granted, most people who like excluding traits or behaviors from their community do.
238U
EDIT: fixed my markups.