For what it's worth, this article has given me ample moral justification for the disdain I show for cold-callers and relationship-based sellers alike (though typically I'll be openly hostile only to the first group): I don't owe them anything, even people I work with over a period of years. As long as they're trying to sell me something, I have the thing they want and not the other way around. What's truly astonishing to me is that so many people I work with don't see the con and think their "relationship manager" actually cares about them and is genuinely trying to get them a good deal. No, they're trying to sell you underbody coating and should be treated accordingly.
I remember one guy, years ago, who ended a 45-second year-end cold call with me with a "Come on man, I have a family. At least hear me out!" I responded, "Get a better job then. I have work to do." As a moral human, I feel sort of bad about that response, but then I remember there's a substantial likelihood he was lying to me to keep the call going to score a sale and the grift depends on me being moral.