I wish people would stop limiting the concept of "interracial" to only black and white. Technically, interracial could even be a hispanic getting fucked by an Asian. Usually, when people are talking about interracial, they're talking about watching a black man fucking a white woman.
Anyway, I only enjoy it when they are not calling attention to the fact that one of them is of a different race. A fuck is a fuck is a fuck, but I get so turned off when they start saying **** like "like that black cock" or "that white ass" or "this latin pussy" or things of that nature.
Also, I'm more likely to enjoy it if it's a black/hispanic/asian woman being fucked by a white guy. That's because I like to imagine I'm there fucking the chick (isn't porn supposed to put us in a fantasy world anyway?). As a white guy, I can't do that if the dude in the movie has a black or brown dick.
Additionally, as someone previously mentioned, I really **** it when it's some 'gangsta' looking/acting guy (which is true no matter what race he is). I can't stand thugs. Sadly, most black guys in porn act exactly like that.