Why does Gulliver work so hard not to be associated with the Yahoos?

Gulliver is offended and humiliated at being compared to a Yahoo. Gulliver must do everything he can to separate himself from the Yahoos, a very different situation from his distinct positions in Lilliput and Brobdingnag. In order to accomplish this, Gulliver does small things daily like using his best manners, eating with a knife and fork, keeping his clothes on, and being as clean as possible. He shows that he can use language, can reason well, and can be prudent and mannerly. Here Gulliver truly feels inferior to the Houyhnhnms in contrast to how he felt with other cultures he had visited.