I think Julian Rios was a bit of a boring performer for example. Tall, good looking classically guy (rare for porn), big dick (I say 7.25x5.5nbp) but low energy and a bit flat.
Guys like Rocco brought more energy.
Personally I find Johnny Sins boring compared to a Manuel Ferrara, Johnny seems more low energy I guess. The guy doesn't have to be a maniac (that's weird too) but you are kind of picturing yourself as the guy so I think one wants to see him enjoying it and both of the partners wired up a bit.
As far as the gay/bi "straight" male pornstars Julian Rios has done a scene receiving a blowjob from a man, so has Criss Strokes.
Johnny Sins, I will just say this, the other male pornstars who turned out to have done gay stuff were mostly surprising to me, but if it turned out Johnny did, it would not surprise me at all. From having watched his youtube vids etc. But I guess nothing is proven yet.