They could habitate any field, e.g., physics, psychology, horse racing, etc., but the politcal ones are easiest to find and study. This piece at meet the g focuses on the species on the political right:

An old social psychology teacher of mine, Professor Alabaster V. Entenswop, used to wax lyrical about his pet hate, Agenda Fuckers � he changed the term to Agenda Whores just before his death by food choking. What�s an Agenda Whore? His definition, cribbed from his red lecture series:

�An agenda fucker. He, or it could be a She these days. They or It decide to center their life and work upon a single political, social or psychological event. They do this without any type of humour or irony, they can change their agenda at a whim

You go read the rest.
Via Ruminate This.