Thus, counter-intuitively, saying 'I don't know' is an indicator of the speaker's knowledge, as he is aware of areas of his ignorance.
Contrast with an arrogant attitude of "I-know-everything-or-can-find-it-out" and the fuck-ups that inevitably follow.
Aside: I would really like to know what the solution to keeping the listings updated was. Or, is that a trade secret? ;)
edit: s/Aide/Aside