It is an interesting question. As far as I can tell, with guys watching guy-on-guy porn, you have a number of different levels of appreciation, besides the basic "They're doin' it!"
I'd like to be Mr. A
I'd like to be Mr. B
I'd like to be Mr. A doing Mr. B
I'd like to be Mr. B being done by Mr. A
I like to watch Mr. A doing anyone (and if he will do Mr B, I have a chance!)
I like to be Mr. B being done by anyone (and if he will let Mr A do him, I have a chance!)
This compares to the simple straight model of
I'd like to do her
If she will do him, then I have a chance (the "Ron Jeremy Rule")
Or, for lesbian porn and straight guys,
They are just getting each other heated up for me
NOT Hey, they don't even need me!
I remember a visit to a bi-polyamerous friend, and, well, things got tangled up a bit, with him, his boyfriend, me, my boyfriend, and higher-ordered experimental topology, when his girlfriend (also bi-poly) came home, took one look at what was happening, and made a mad dash for the stairs followed by the slamming of the bedroom door. When the story came back later, it turned out that she wasn't mad, or upset, but that she just got so turned on that she had to take matters into her own hands! (I think there was some element of her wanting to join in, but she didn't want to upset things with the added complexity of "icky girl parts")
As far as the OP goes, I'd love to hear more of her views too. Hey, if I can watch Whoopi, Barb, 'Liz, and Sheri, why not on my favourite porn site, too?
Perhaps it's time to retire the old belief that anyone claiming to be a young girl on the internet is really a 45-year-old guy sitting in his boxers in front of the monitor. On the other hand, I think I need a little private time with that image. 🙂