I think Davinas part is probs more scripted than the rest...because Endemol know that more people will be watching the live evictions etc, so that she has less of a free reign
Dermot has a later night spot, where he can get away with more..ie, showing the "porn" clips of Caprice....and then they can edit it for the earlier slot shown next day
Russell doesn't seem to be scripted at all...and as he is only on E4, less people will watch it...so he can just go off at a tangent whenever he wants