What's the difference between i.e. and e.g.?
"smooth and sleek" (1909); "ingratiating, unctuous," 1924, from smarm + -y (2). Related: Smarmily; smarminess.
[1924+; origin unknown; since the earliest attested uses have to do with hair oil, it may be a vague blend of smooth, smear, palm oil, cream, etc]