I often wonder how much of this is innate in the characters, how much is very clever editing, and how much of it they are prompted to do, either because they know this will make "good" TV, or because they select people with this sort of dynamic.

I have a designer friend who was virtually stalked by one of the past contestants on Project Runway. She'd turned down the opportunity to go on it herself, and has never regretted doing so.

Classic bully behaviour - isolating someone, whisper campaigns...