Have you ever noticed that most words starting with "Sn" have negative connotations? Snide, snob, sneer, snot, snipe, snivel, snoop, snore, snub, snark, snitch.
What two animals start with "sn"? Snails and snakes.
The most famous "sn" acronym? Snafu.
Rare counter-examples: snazzy, snog, snug, and snow.
I wonder if it's the fact that to pronounce "sn", your face takes on the appearance of a sneer....