If spending the weekend at a convention in another state is what's needed to make the sale I do that. If drinking with a visiting client until 2am is what's needed to make the sale I do that. If coming in to the office when there's no need and I might get sick and die and more importantly not be able to make sales, I don't do that.
"Sales" is a very broad role to the point where I think someone saying they do it is closer to someone saying they "make things" or "perform services" rather than "software developer" or "lawyer". It's more of a department than anything. Experiences working in it thus vary greatly.
I work with people in sales, and IIRC they were the first ones to start to work from home, days before the software development teams started to follow suit.
It's not a class issue, but a company or even team issue.