In any porn film, amateur or pro, a certain suspension of disbelief is necessary to enhance the fantasy. Gosh, I didn't know car mechanics liked to fuck guys while wearing dirty overalls!
Same thing with, Wow, that straight guy is so turned on by that skaggy old guy in Amateurstraightguys that he can't resist sucking his cock.
The problem comes when a site doesn't know how to make the fantasy convincing.
On Bukbuddies, for example, they've started including little profiles of the models, which invariably say they're "str8." But then the same guys show up on their sister site, Hornyhoundogs, taking it up the ass!
Straight College Men, on the other hand, really has me believing that most of their guys are straight, or start out that way. I don't think Boston Paul had done anything with a guy before he got a whopping hardon in the bathtub being played with by the guy who runs the site. That was hot.
Sean Cody well, he has about zero credibility on this subject at this point. At least he no longer tries to claim that ALL his guys are straight -- I just doubt whether any of them are, except the guys who only do solo.
As for self-loathing, blah blah blah, get over it. There's nothing PC about sex, ever. It's messy and dirty, naughty, forbidden, stuff you'd die of shame if your parents found out you did it. Otherwise what's the point?