The general over-reliance on anecdotes is counter productive. I met a gay person before and they were like this, I met a Christian before and they were like x. I met an Italian before too! They were like x. You realize that every subgroup or community is going to have ignorant people or assholes in them right? Meeting one person is not going to be representative of every single person in said group. Pick any group, any subculture, I garuntee you there will be plenty of people who fits every negative trait you can think of.
Instead of saying x group is like said trait, just accept you met an asshole/idiot, and move on.