I’m glad to hear you say that because life experiences usually prove that in regard to behavior sciences there is no such thing as definitive. From your posting it sounded to me like you would feel the need to ignore your impressions for the sake of the “written word”. I have seen psychologists do this and it drives me nuts. They will diagnose certain children with autism or other things based on the checklists even when life evidence gives them pause.
So can they negate the checklist? No, but they can use the discrepancies to look further into what is before them and possibly start storing up their own data base of exceptions. Those exceptions are also people.