Slytherin house is historically associated with the belief in blood purity, valuing pure-blood wizards and often looking down upon Muggle-borns and half-bloods. This view, stemming from founder Salazar Slytherin's beliefs, has led to a reputation for elitism and prejudice within the house. However, it's important to note that this viewpoint does not reflect all Slytherin members, as the series progresses, showing a more diverse and complex portrayal of Slytherin students.