One common misconception is "I have done it this way a bunch of times and nothing bad has happened, so it must be ok to do it again"

I was on a kitchen remodel where the carpenter had convinced the home owner that I was trying to charge too much because I would not tape wires up and burry them behind the new cabinet. I insisted that we run new wire to the attic and instal junction boxes. There was a heated discussion where the carpenter told the home owner that he had dun it that way a bunch of times and nothing bad could ever happen.

This carpenter/handy man, had been working for the HO for some times and they had a friendly relationship. I was called in because the building inspector discoved that he was doing electrical work without a licence.

I refused to do it his way and walked off the job. I got a call the next day to come finish it my way.

To this day, that HO probably believes that I just wanted to rip him off and that taping up the wires and stuffing them in the wall would have been fine.