Oh the box isn't so black. That's not to say that everything
   will make sense but consider:
   a) We're communicating
   b) We have generalized knowledge of patterns observable through
   behavior.

   Yes, there is lying. Yes, many of the methods used to
   "mind-read" fail. In fact, I say it frequently:

   MINDREADING IS IMPOSSIBLE

   But... you _can_ understand them and have a seat and look around
   their house, once you understand their own patterns.

   That's not to say they won't surprise you but up to a limited
   point, it's certainly possible. And the more patterned someone
   is, the easier it is to step in their mind. Might not see
   everything but you can see a lot.