I'll be the first to jump in with full disclosure. I do not find male on male porn arousing in the least, but what I do find arousing is either shemale on male porn or forced bisexual action from a dominant wife over her husband.
I was watching a video earlier of a wife and her female best friend dominating the husband. They had him bound and watching while the wife had sex with another man, then the friend pegged the husband while the wife watched while having sex. The husband was forced to suck the other man's cock while his wife and her friend watched, laughed and teased him, eventually leading to the husband licking the other man's cum out of his wife's pussy.
Don't ask me why I found it so arousing, because I'd never want to be in the man's place while my wife had sex with another man, yet it was extremely arousing to me.