Bisping is the perfect "bad guy" for the Americans: English, confident (see cockey if you're American) and almost always wins (13-4 with only 1 clean loss).
The only guy who i think got more hate than Bisping was Paul Daley who since leaving the UFC is not really in the firing line - i sense Daley is hated for the same reasons as Bisping except with the added bonus of being black.
After Bisping TKOs Belfort i hope he wipes his arse with the American flag as thousands of Brazilians cheer him on (joke)
I hate Paul Daley but that's cause he is a douchebag. Also my hate for Bisping has nothing to do with being British. I don't care where a fighter is from really, fighters only get brownie points if they are from my state. But I don't care if you are Brazilian, Canadian, American or whatever. Ross Pierson is a guy that most Americans root for. Even though he wasn't skilled Ross Pointon was a fan favorite as well. Douche is douche though no matter where you are from. Just like Koscheck is a douche bag that translates to any language or region. The only people that don't hate Kos are cocky ass wrestlers that are just as big of douche bags as Kos.
Also race has nothing at all to do with Americans hating Daley. Nothing at all.
EDIT: I'm actually borderline offended by the assumptions you are making. Especially with the race comment you slid in there. To imply that Mike or Paul's hate has anything to do with anything but their attitudes is incorrect. Most British fighters are received just fine.