I went on the Carnival site last week to look up the answer to a question posted here. A day later a PVP called and said he'd "noticed" I'd been on the site and wondered if he could help me. I told him I had a wonderful TA and he just said that he hoped I'd cruise Carnival again. He never said that he could get me a better deal.
I don't think there's really anything so wrong in what they're doing (and apparently it works, or they wouldn't be doing it!). I imagine that people who are inexperienced cruisers without TA's might like to hear from a PVP.
Paul, you might have been in the same position. Had you been searching for a cruise on NCL before they called you?