In general, crime fiction is seen as belonging to a lesser class of writing than literature.
Crime fiction is escapist, literature is 'worthy' or 'a work of art'.
It is difficult to determine just where this borderline lies, even if it is nothing more than a marketing exercise by book publishers. Pulp books of the fifites get a lick of paint and are easily repackaged as literature at a higher profit margin. Raymond Chandler wrote pulp stories but is liked by intellectuals because of his witty turn of phrase and is often seen as more 'legitimate' than his contemporaries such as Hammett. Even Jim Thompson has found new respectability as a 'great American writer' with new editions of his work priced to match this status. Some crime writers have felt limited by the genre 'ghettos' of fiction.