I've had this conversation before. Same sort of argument that if it's a tranny banging a chick then is it possibly more gay to watch a guy banging a chick? Very philosophical question indeed. I wouldn't find it "gay" just a little strange and a sort of novelty seeking. Even if I found out someone had fucked a tranny I wouldn't say they were necessarily gay...just a little bisexual and possessing much more kinkier tastes than I. However, I have to say that I would put it on the same rank of weirdness as finding one of those real sex dolls stashed away in a friends closet. I think it depends on one's openness and novelty seeking. I'd imagine this person starts out watching straight porn, then threesomes, lesbian porn, etc....until maybe tranny porn. And perhaps in real life maybe the same thing - someone tires of safe hetero vanilla sex, and turns to bisexuality, polyamory, yiffing, felching, snoodling, clear plating, daisy chaining - and so the story goes. Ah I guess I felt like typing out this long response because I'm reading a book that touches on the topic. It's about sex, evolution, and consumer behavior.