And I have been in the situation where we didn't ask enough of the personality questions, and we did take the guy out to lunch. It turned out he was completely unresponsive to requests to work, but he kept himself busy with rewriting our stuff that worked so that it had problems!
None of that came out in the interview or at lunch.
"That that is, is... for what is that but that? and is but is?" Shakespeare, Twelfth Night, Act IV, Scene 2
"Yet THAT which is not neither is nor is not That which is!" Frater Perdurabo (pseud. Aleister Crowley), Liber CCCXXXIII, The Book of Lies