Chapter Six is the first chapter where the contrasting worlds of Wuthering Heights and Thrushcross Grange collide, and it is clear from the description of the Grange that Heathcliff narrates to Nelly that they are two very different worlds indeed. The luxury of the Grange with its "crimson-covered chairs and tables" and crimson carpet is very different indeed from the harsh, utilitarian nature of life at Wuthering Heights. It is clear from how Heathcliff narrates what he and Cathy saw to Nelly that he has nothing but contempt for Edgar and Isabella. Note how he describes them fighting over a dog:
The idiots! That was their pleasure! To quarrel who should hold a heap of warm hair, and each begin to cry because both, after struggling to get it, refused to take it. We laughed outright at the petted things, we did despise them!
Heathcliff clearly therefore despises the Lintons because he finds them so pathetic and ridiculous. Although Cathy initially shares these views, it is clear that by the end of the chapter, by which time she has been carried into the house and settled on the sofa and then waited upon, it is clear that she does not rage in anger as Heathcliff would have done. By the end of the chapter, it is clear that Cathy has changed in her opinion of the Lintons, as the next chapter describes very clearly.