I won't denigrate your dad or the story. It's all part of the territory. I would guess the seasoned pros knew what was up and the young salespeople got a good training lesson.
I spent a life in sales, recreational vehicles of sorts. I ran a bit of a different type of shop, low key and dependent on repeat and referrals. People came to work for me because they loved the product and the lifestyle. Most weren't professional salespeople as I didn't really get along with that type. The typical customer comes into the door of a sales establishment with a chip on their shoulder and an intention to beat every dime of commission out of a deal. Considering we worked with all the other dealers and their salespeople and got a good view of the shenanigans going on and the attitude was understandable. OTOH, we also saw first hand the shenanigans the public pulls on salespeople. I had a little saying that took new salespeople a while to understand, buyers are lairs and sellers are worse. Over time they'd learn just how cynical and true the term was. Salespeople generally developed in two directions. Most at first did very well with an excited attitude and love of product. They's shrug off all the nasty things customers did because they were doing something they loved. But over time, six months, nine months, the persistent dirty tricks, lies, and general inconsiderate nature of folks would drive off the good hearted salespeople. A few, not many, would learn to counter the dirty dealings of folks, let it roll off their backs and they got better at giving it than receiving it. These folks, after a year or year and a half, would move on to other locations where they could make much more money. We stayed a small backwater operation mainly because I liked what I was doing and how I was doing it. Money was never the score keeper. But in the sales game that is no recipe for success.
Much like we get the government we deserve, salespeople are what they are because the public are what the public are.
“While you live, shine / Have no grief at all / Life exists only for a short while / And time demands its toll.”