All 4 Uses

unctuous
in
Harry Potter (#4) and the Goblet of Fire
(Edited)

Karkaroff had a fruity, unctuous voice; when he stepped into the light pouring from the front doors of the castle they saw that he was tall and thin like Dumbledore, but his white hair was short, and his goatee (finishing in a small curl) did not entirely hide his rather weak chin.
Chpt 15

unctuous = overly ingratiating (trying to gain approval)
"Mr. Crouch....Mr. Bagman," said Karkaroff, his voice unctuous once more, "you are our — er — objective judges."
Chpt 17

unctuous = overly ingratiating
He had dropped his unctuous tone and his smile now.
Chpt 17 *

unctuous = overly flattering, charming or ingratiating
"I have, sir," he said, and although his voice was very scared, Harry could still hear the familiar unctuous note in it.
Chpt 30

unctuous = overly ingratiating

Definitions:

(1) (unctuous as in: annoyingly unctuous waiter)
overly flattering, charming or ingratiating (trying to gain approval)
(2) (unctuous as in: unctuous frying pan)
oily or greasy
(3) (meaning too rare to warrant focus)
soft and rich in texture; or expressing rich satisfaction