this sort of procedure works on a particular psychetype, keep in mind there is not a lot of particularily bright people in prison.

about a quarter of subjects dont fall for it, because even so called professional interogators are pretty obvious to someone accustomed to thinking before acting.

also an actual member or neophyte of a crime organisation knows better than to start lipping off about past criminal activity. having loose lips wont get you an audience with a real mr. big, it will end up precipitating a tragic accident.