I consider myself bisexual. The idea of sex with men has been a part of my desires, and its happened within the last 3 years, and this is no doubt influenced by the anonymity of the internet and the wide range of porn, further fuelled by anal masturbation and self exploration. (and my subsequent addiction). I still PREFER women, and I think women are visualy more appealing, and I think sex with a women is more enjoyable, more variety. Even though I really like cocks, and the feeling of a cock in my ass, I sometimes struggle to watch gayporn because I don't think it is as visualy stimulating as scenes between a man and a woman. I find I actually desire a man's cock more than I do any other area of his body, but I can find the whole package appealing. I find a woman's bum to be far more beautiful than that of a man. This is why I rate my "straightness" higher. I also want to settle down with a girfriend, get married and have kids one day.
I've read and understood that a man can receive more pleasure from prostate stimulation from anal sex than he can from having sex with a woman. There are studies to back this up, or so I am told. Certainly the orgasms I've had from anal play back this up (people should look into an aneros, and how to use it properly, simply mindblowing), if done properly it can leave you wimpering and exhausted to the point of not being able to move. Surely this information alone would tempt a "100%" straight man into exploration or curiosity.
Penis envy is a common thing amongst men, and I think that if you enjoy comparing your cock to other people's, then there is a desire and appreciation and lust for a large cock and hence an attraction to the male sex organ. I think its impossible to be 100% straight, but I find women are more willing to admit this than men.
Maybe the ideal for me is a trans!
Sorry if any of that offended people, its just my view!