Some general thoughts...
Bad instructors, bad students and bad pilots exist within society just as frequently as there are bad drivers and inept/bad people in general.
I once belonged to an organization who had a fleet of general aviation airplanes and tended to micromanage safety with regulation upon regulation. We had flight instructors and pilots from all walks of life. Not many were professional pilots or professional CFI's. One CFI was a retired dentist who had some strange ideas about how to operate an airplane. His credibility was very high among the pilots with minimal experience and/or ability.
I'm not sure a student can properly recognize a good instructor when they see one. If one doesn't know right from wrong, how can the instructor be properly evaluated without constantly seeking the truth and applying the knowledge to the babble that exists? Kind of like the evening news and politics, which is how bad politicians (I know that is redundant) get elected again and again.
