[optimisticcynic]

All the housemates were screened for the purpose of the show, and the traits likely to infuriate/pull the heartstrings of the public were sought to ensure an audience and revenue from voting. That's why it makes no sense to me to have a favourite at the start. Whomever you settle on as "a thoroughly nice bloke/lass" showed something in the interviews that made the BB team think "if we do x,y,and z, this person will turn into an utter **** and the ratings will soar". Even thoroughly-nice-Chris showed there's more to him when his question to the public was "who is my biggest threat?". You need to have a fairly pumped up sense of self, despite his protestation to the contrary, to view others as threats to your own success. He could have simply asked "who do the public want me to nominate?" which would have sounded much less grandiose.