The problem people have is that they place people into their own categories and boxes depending on several different personal factors.
It can be Rumors, appearance, first contact, or just a mixtur of things. This often happen without them having nearly a full picture of the person they prejudge in general.
So if you end up in someone's "Idiot" Labeled category or box, your pretty much screwed to stay in that box no matter what you say or do. Because that person have convinced themselves that your an idiot and at fault for everything you do while they are the superior. Your oppinions are not important and what you say don't count for anyhting at all.
and the only advie I have if you end up in someone's idot category is to dismiss the person right back unless you have a very good reason to prove otherwise. Theres 6billion+ more people in the world that is probably more worth of your time than someone who your likely to not get anywhere with anyway.
It just wastes your energy even putting thoughts to people who clearly dislike you from the start.
Its difficult to do, but if everyone in the world could meet or see a new person and see them as a blank slate of paper and take notes as times goes, the world would probably be a much more pleasant place.