As a (slight) aside, I never cease to be amazed at the standard of flying of SOME experienced PPLs. In particular, poor RT, lookout and general situational awareness. It is often said that a PPL is a 'licence to learn' and there is a huge variation in how that is applied, post qualification. Some seek to develop and retain their skills, even if not doing any further formal training, while others seem to just 'jump in and go'.
I would like to think that any prospective FI would have a good look at themselves first and their attitude to every flight (do you self brief & debrief for a start....?) before going anywhere near a pre-entry flight test.