Garish, gaudy mean bright or showy in a tasteless way. If you are not trying to insult the socks, you could call them flashy or loud.

They clash with everything you could possibly say.

Animal metaphors can be used to describe other animals using the word “who”. Many examples include pets, talking animal characters in stories, and wild animals being captured in a nature documentary, just to name some examples. Generally, if the animal’s name or gender is known, it should probably be personified. (Note that even when talking about animals of assumed personhood but unspecified gender, I still use “it” where a person would be “they”—a human-centric bias).

So the dog reincarnated as a person, who I presume is now sentient and a main character in the story, should absolutely be referred to using “who” both in the present and in any references to her or his or her past life as

a dog.