Negating adjective ending with ない

Question

According to this answer there are two types of 〜ない adjectives, those that contain 無い (like 情けない, つまらない also falls here) and those that derive from archaic なう verb (like 危ない). For the first 無い type, how natural is it to negate such an adjective?

Google finds relatively few instances of, say, つまらなくない, some of which a not real negations but questions like "boring, isn't it?". However where are also cases like つまらなくない話 and I see how it might mean "not boring, but still less than interesting". However I can't quite comprehend what kind of person 情けなくない男 would be. In most (all?) cases there's an antonym to 〜ない adjective, so the utility of negation is questionable.

So, is negation of such 〜ない adjectives considered natural, or do you normally avoid it?

Answer 1

Saying something is つまらなくない doesn't mean it's interesting; saying someone is 情けなくない doesn't mean they're hopeful / sympathetic / happy. By analogy, we also can -- but don't often -- negate negative adjectives in English, to similar effect: "this book is not uninteresting, that scan is not entirely illegible, the person over there standing by the ice-cream van is not unattractive," etc. etc. The double-negative in either English or Japanese indicates more of a middle-ground quality -- not great, not awful, kind of "meh".