An very interesting read!
In the circles that I have moved in, sales people have always been distrusted - whether they were hawking real estate, used cars, encyclopaedias, electronic security systems, high voltage switchgear, fruit and veg at the local market, or whatever. After reading this account, I am now reminded as to why this distrust is still so prevalent. As my uncle would say, they all seemed well endowed with plenty of "what the cat licked its tail with."
Mind you, this was a handy quality for a Maintenance Technician to have, when it came to explaining to the client why the said piece of equipment failed to live up to the expectations that the Sales Engineer assured them it was capable of delivering. ("If you can't Blind with Science, you can usually Baffle with Bull$h#t").
I have been working now for over 45 years, and have only once had my "employment terminated". They gave as their reason that I "was not the sort of person they wanted for the job." I fully concurred with that, and told them so. The "sort of person" they were seeking was a loud, arrogant, foul-mouthed backstabber, with a generous measure of @$$ licker thrown into the mix as well. I told them that, too!