I've recently begun taking it as a challenge to get the sales person to hang up before me. Like I'll start getting unsociably angry - trying to work up whines and cries or infantilize them (e.g. "nononono, I'm talking. I'm talking. Are you done? You'll speak when spoken to."). I treat it like a sumo match. I've been working through a routine where I am "willing to critique their silly little sales pitch after they pay for a retainer and sign an NDA like the rest of my clients." I've stopped making eye contact and responding to people outside of grocery stores and putting no tip if I'm not sitting down at a restaurant.

It's made me excited for sales calls. Once I saw how the sausage is made, I've only gotten more militant in the ways I handle these people.