@ How to not fall victim...
"I do not subscribe to the "they are only doing their job" philosophy."
I do subscribe to that philosophy - they are being paid to talk to me and if I happen to be a thoroughly nasty person who mocks and insults them in an attempt to make their life as unpleasant as possible, that's just part of the job. It's simple market forces. The more abusive we are to these people (advertisers/scammers - same difference), the more they will have to pay their staff to put up with it. The aim is to drive the staffing costs so high that it's no longer economical to phone me up to sell their tat.
Alternatively, in the UK, tell them you want nothing to do with their organization and will consider it harassment if they call you again. A reasonable person in possession of that information would not call again. When they do call again, quote the Protection from Harassment Act 1997 at them;
(1) A person must not pursue a course of conduct-
(a) which amounts to harassment of another, and
(b) which he knows or ought to know amounts to harassment of the other.
(1A) A person must not pursue a course of conduct -
(b) which he knows or ought to know involves harassment of those persons, and
(c) by which he intends to persuade any person (whether or not one of those mentioned above)-
(ii) to do something that he is not under any obligation to do
(1) A person who pursues a course of conduct in breach of section 1 is guilty of an offence.
(2) A person guilty of an offence under this section is liable on summary conviction to imprisonment for a term not exceeding six months, or a fine not exceeding level 5 on the standard scale, or both.
I scared the life out of some kid from Beneficial Finance after I'd explained that the "DNS" note on my file meant Do Not Solicit and that it was put on there by the 2nd of their phone-monkeys to call me. Cue some very hasty apologising from his line manager.