I recall an I&T I did in April where the client had requested a CU change and I tested out the lighting circuit reading >299MΩ but the insulation on the bathroom ceiling light was totally shot at! So always worth a little investigation.
I see it in all sort of fields, many highly divorced from matters electrical. I'm afaraid that some people have become so focussed on their high-tech gizmos that they fail to use their eyes and common sense. Technology is a useful aid, but it should not come to be regarded as a panacea, or a substitute for common sense!
...one sees some frightening examples on 'Air Crash Invesigation'. Some modern-generation pilots will believe the high-tech displays telling them that their plane is not stalling in a situation in which it would be totally obvious to any 'seat-of-the-pants' pilot that it
was stalling!
Kind Regards, John.