Emmet's an interesting specimen. I mean, he is in more ways than one, but consider how he must perceive himself. He settled in a part of the world where few people have any idea what a wombat even is (most seem to assume he's some sort of strange groundhog)—so he rarely encounters any members of his own species. He's completely uninterested in romantic relationships and he rarely goes out in public. His sense of fashion is entirely determined by what is convenient and utilitarian.

In short, Emmet has no idea if he's attractive or ugly. His outer appearance is completely aligned with his self-image, which may have to do with why turning into a kangaroo was especially traumatic for him.

Though if he keeps going on "time missions" he's going to have to start caring about how he presents himself eventually.

Headshot sketch by  Setrael