SpikeSome TV Tropes links that my son told me about this morning:

Affably Evil Characters vs. Evilly Affable Characters:

“There is absolutely nothing separating [Affably Evil villains] from being normal, polite people except for the fact that they want to Take Over the World or use human souls to power their Artifact of Doom. They’re not the Stepford Smiler ā€” their affability is a genuine part of their personality, not a mask…” Read More

“Evilly Affable characters are villains whose polite mannerisms only serve to enhance their evil. While they may seem like pleasant people, this affability is only skin deep; they can run 6 million miles beyond the Moral Event Horizon before breakfast without ever breaking their mask of being a nice, amicable person…” Read More