It's kinda weird, but...
I can't ship Sam Winchester with men.[ramble]
Dean, hell, he's got chemistry with every man he's ever been paired with in a scene. Don't know why, but there's a way that Jensen interacts with people and especially men, that makes me want them to have sex with him. Or you know, to just see them together.
But when it comes to Sam, the only time I want to see him with someone, it's with women, every single time. Put him with a guy and... nothing, but put him with women and it's sizzling.
The only male character I'd ship Sam with, is Dean, and even then only when Sam's evil. (mostly because it's the only way I can overcome the incest factor)
It just works that way with some characters, for me at least. It's not even that there's anything in canon that says Sam has to be straight, he's never hinted one way or the other, it's just that I don't see any sexual or romantic subtext between him and any of the other male characters.Whereas with Dean, he can look at boobs all he wants, look at all the het porn, and so on onscreen, but put him with a guy and it's whoa...I just want to see (read) a scene of them pushing him up against the wall, or bending him over a table and take him.