Agreed. I probably won't catch a bug that the tests wouldn't also catch unless it's obvious. I'm looking for things like:

  -Is this duplicating something 
   else?
  -Should this be part of this 
   object?
  -if I come back in a year, will 
   it take me 10 minutes or an
   hour to understand it?
  -is this necessary?
  -should I approve this but add a 
   task to the tracking board to 
   figure out if this should be 
   done in the service instead of 
   the client?
  -etc