One way to hold this word: it is the thing coming out of a nose — sticky, and nobody wants it near them. Both meanings sit on that one picture. In the first, it is the stuff itself. In the second, the stuff is pointed at a person: someone you would rather not be near, who acts as if the rest of us are beneath them. The blunt, rude feeling of the word travels with it either way.
From the word’s history
From Middle English snot, from Old English ġesnot, from the same base as snout; probably a sound-copying word, like sniff and snuff.
從中古英文 snot、古英文 ġesnot 來的，跟 snout（動物的口鼻部）同一個字根。它很可能本來就是模仿吸鼻子聲音的字，跟 sniff、snuff 同一家。也就是說，這個字從一開始就長在鼻子上。
Wiktionary entry for snot (kaikki extract, source_ref kaikki:3f6f69a190036ae4:459839590): "From Middle English snot, snotte, from Old English ġesnot ... from the same base as snout; ultimately of onomatopoeic or sound-symbolic origin (compare sniff, snuff...)."
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