I think we're getting a little off the path here, guys. "Ain't misbehavin'" isn't litotes, neither is "no unkind words". Litotes is the converse of hyperbole: it's the deliberate use of understatement for literary or rhetorical effect, so "not half bad" qualifies, as does "pretty good" when you really mean "very good"; you don't have to have the counter-negation "not un-". A double negative signifies an affirmative, if you're a little pedantic, or a negative in most colloquial speech. Curiously, there's no such thing as a double affirmative signifying a negative. Yeah, yeah!

Steve