How can we tell that this is the case? Well, to make an interesting TV series, FBI agents must be paired with:
-- mathematicians (Numb3rs)
-- psychologists (Criminal Minds)
-- anthropologists (Bones), or
-- crank conspiracy theorists (The X Files)
These are not the sort of people that are stereotypically "interesting". Yet, these are what has to be added to an FBI drama to give it any sort of hook at all (at least since 1974 and the end of "The FBI Story".) We can only conclude that FBI agents, in isolation, are more boring than any of the above professions.