If I repeat myself, I am sorry. Moreover noir, I am more interested in the dark journey. I like to see my characters venture off into unfamiliar territory and see how that changes them. Like Heart Of Darkness and its contemporary Apocalypse Now.
Noirish characters are ones who took that dark journey and didn't come back completely whole. This doesn't mean they turn completely to the darkside, but that they incorporate elements of it in their lives.
The Dark Journey contains more truth and says a great deal about the character just by the way they handle themself through out the story than I think noir does.
My goal is to use noir just as a minor color or shading in my stories.