Reality TV is about two things - Ratings and Money. It is not like sport which has rigid rules and a level playing field. This is crucial to understand. The more the entertaining the show, the more viewers. Viewers will not switch on to Big Brother to watch the house getting along swimmingly - they want conflict and lots of it. Failing that, they want love, lust and hopefully, sex! So the shows will often swing a lot - especially on commercial channels.
So as gamblers how can we use it? The first thing is protect yourself against the 'Black Swan' that if occurs will wipe you out (or give your betting bank a bloody nose). Looking closely at the shows and trying and predict how things will pan out is normally good but you will miss things - being late to things is usually as bad due to the market having shifted - you can't sit in front of Big Brother for twenty hours a day (unless you are a student).
So the point is to not leave yourself overexposed on a single possibility - no matter how unlikely. If Manchester United go a goal down at home, laying 1-0 at 1000-1 is sensible because it won't happen due to very fixed rules. It TV betting it may happen at a producers whim - Nikki Graham re-entering the house, for example. Recently, the phone vote scandals and crackdowns have seen a reduction of these spontaneous and random rule changes that cost the viewers money but it still can and does happen.
Laying Sylvia to go as third eviction of Big Brother, as someone did last summer at 1000-1 cost someone badly - fine if you have £100,000 in your account but risky if you have £2000.
Diana Vickers getting Laryngitis is another good example of how fickle fate can be to the gambler. It killed her chances stone dead.
So in summary, if possible, prepare for anything.