One reason for this is, I suspect, that people are thinking that any criticism of Rudd's family is not nice, and they decide to punish the Liberals for it, despite the fact that it is the media coming up with the stories, not the government.
Secondly, surely everyone has noticed that when Rudd says "we'll take a battering in the polls" or "this is embarrassing", it doesn't hurt his polling at all. I think he has recognised and will keep using the magic formula. Maybe it is some sort of Jedi mind trick, or a pact with the devil, and the way for the public to be reassured that it isn't supernatural forces at work is to see it deliberately put to the test.
My challenge to Kevin is therefore to demonstrate that he can be unpopular by doing something really wrong. How about being caught on camera having sex one night with Julia Gillard on the grass under the flagpole on top of Parliament House? If all he does, while brushing grass off his suit, is to look sheepish and say "well I have to acknowledge this is very embarrassing, it will put a strain on my marriage and I expect to take a battering in the polls" and next week there's another 5% increase, then we will know there is something sinister about him.
Update: I wrote this before I read Matt Price in The Australian this morning. He makes a similar point:
At this rate, Rudd could be captured on video wearing leather bondage gear while snorting ice - and the punters would still find some excuse to look kindly on the Labor leader.I bet in his heart Price wanted to use sex with Gillard as an example, but he has to get on with Rudd and his minders.