What an odd thing to say… For one, “slippery slope” is literally the name of the logical fallacy you’re doing here.
But also, think about what you’re saying for a moment. How does accurately describing a person’s behavior dehumanize them? Are we just supposed to never acknowledge shitty behavior in others?
It’s kind of the opposite… I’ve never heard an animal described as “deplorable”. I’m not sure they’re capable of it? So if anything, the term is humanizing.