An example of an affable villain that I enjoy is Walter White. He started off pretty affable, but he clearly became faux affably evil during moments people insult his ego. I think the moment he truly become faux affable are his passive-aggressive response to Hank's unintentional insult in Breaking Bad Season 4.
Tighten was also somewhat affable with his relationship with Megamind, until the former ended up being betrayed and became way worse.