Well, the thing is though, there are cases where Slytherins have the opportunity to show other sides, and don't. That said, I see your point.

But you're right... some are probably "conditioned" to those feelings. And in fairness, Harry IS the main point of view here, and my Dad was actually telling me about a book he read where this character thought he understood all the things that happened to him, when really, his point of view was wrong.