I think the dislike of Leeds stems somwhat from bad blood between Derby and Leeds who were huge rivals for the title in the early/mid seventies...plus you had the whole Cloughie angle as well.
Having Dennis Wise as manager doesn't inspire people to like you either, although that's out of the way now at least!
Well not just with Derby fans (and Man Utd fans at any rate).....but it seems that the whole country hates Leeds and Leeds fans. I'm unlike many Leeds fans in that I actually thought the club were absolutely stupid to sack Clough after 6 weeks. Five Years later he won 2 straight European Cups with Forest. So in retrospect, how much sense did it make? Whoever came after Revie wasn't going to be like Revie, and certainly the old Revie players that came in as managers in the 80's certainly didn't bring success with them.
But anyway, I just hope we have a brighter future.