Part of it is that text communication has no nuance, so while what you said may have gotten nods from some criticizing you here, on a text based message board you're getting raked over the coals.
I did door to door sales for 1 week when I was at BYU and felt like I'd touched a hot stove. It wasn't for me and a large part of it was that I saw the dishonesty in at least the company I worked for...and I saw the same dishonesty across many of the similar companies.
So while I haven't dealt with salesmen as much, I was one briefly and had a pretty sour opinion that hasn't changed. I even heard a whole pitch the other month in Utah of someone from the "marketing department" at a place selling windows where this home could be a demo/model in the neighborhood and I just rolled my eyes. It's like the pitch hasn't changed in 20 years.