I think that sometimes a prejudice attitude can be caused by bad experiences with a particular group of people, but most of the time people are prejudice simply because their family and friends are prejudice. When the people you are closest to show strong contempt for a certain type of person your whole life, you eventually grow up hating that person too and all people like them. So basically I think things like racism and sexism are inherited from our families.
Regarding the subject of "rednecks", I don't think it's right to say people who dislike them are being prejudice, not in the same way as disliking somebody who is a different race, religion, or gender. To me being prejudice implies a hatred or fear for a group of people who can't help being who they are. Rednecks, along with some other groups of like-minded individuals such as Hippies and Gangsters, all choose to fit the label society places on them and they should accept the consequences that not everybody is going to agree with their views on how life should be.
Am I making any sense?
As for the OP, he might have a different reason for hating "redneck things" in an intense way. It's OK for him not to like the redneck culture, he just shouldn't allow it to make him do something he'd regret like going out and hurting/killing somebody who fits the label.