I still believe that the ones who get voted out don't - the result is decided beforehand by the producers etc. Emma's record's flagging a bit, so she needed to stay a little longer. DJ Spoony's ... well ... a DJ, and they do tend to have a certain image (right or wrong). I don't know him, but I actually thought he did pretty well that first week.
I don't know much about Mark, and don't particularly like him, but I remember Dawson in a game show where celebs had to answer questions on school subjects. He ran away with first place and everyone jokingly said what a swot was. I really do think he swotted for that because he couldn't stand to lose. I wonder whether he's going to be the same here. He seems fiercely competitive, wanting to win at all costs (natural in a sportsman, I suppose), but I wonder how far he'd go to win.