Excellent post RTN11 , I have been on the rough end of one of those 'I dont really want to be here' Instructors !
9 months after professional flying training I am just about to look at FI schools as its always been something I was passionate about doing , maybe because I was lucky enough to have had two excellent instructors myself for the PPL!
Both are now with airlines and both say instructing was the best flying they ever did!