"A thought to throw into the equation of what makes a Noir/Neo Noir is an individual internal factor. It's subjectivity. Noir is in all of us. Think of us all as having an internal tuning fork, these tuning forks are forged by our life experiences which are all unique. When we watch these films their degree of Noir-ness resonates with us differently, so we either "tune" to them or we don't. The amount of "tuning" (I'm appropriating this term from the Neo Noir Dark City (1998)) to certain films will vary between us all also."
So lets hear your thoughts?