Earlier quoted context omitted.
This sounds like a company I would never want to work for. No one is positive and happy all the time and having to fake it "as a job requirement" sounds wrong on so many levels.
I’m sure you already know this, but don’t ever do sales.
I did not fake "happy happy joy joy," but I also did not allow self absorption to inject my mood into my business. My model is that sales is a career that involves having structured communications.
That was a lifesaver for me when feeling depressed, because I could focus on the structure of what needed to be accomplished rather than the unstructured touchy-feely business of "getting along with people."
I suggest that "YMMV." Salespeople are not all the same, and some break preconceptions and stereotypes hard while being successful at what they do.