Based on my personal experience of getting onto the contact list of an extremely persistent Cogent sales person, mostly, I am morbidly curious what their CRM system looks like for cold and stale leads, and how often these sets of non-responsive leads get passed on to new junior salespeople. And exactly how many of those sales people there are and what policies/management structure they work under.
It took a fair amount of effort and many strongly worded responses on my part to eventually get my personal cellular phone number removed from their CRM system (or at least marked as a do-not-contact).