Why does Cathy treat Joseph hareton and zillah so contemptuously?

Cathy treats Joseph, Hareton, and Zillah contemptuously because she perceives them as lower-class, uncultured individuals who lack sophistication and refinement. Her disdain reflects her own social ambitions and her desire to align herself with a higher status. Additionally, her upbringing in a privileged environment leads her to look down on those she considers beneath her, revealing her character's flaws and the impact of social class on personal relationships in "Wuthering Heights."