I would suggest, if we are going to have such polls, that they be somewhat more sophisticated. And that 3 or five point scaling be used instead of simple binary choices.
The simple fact of the matter is that the majority candidate in each party may get the nomination, but will lose the general election if they are unacceptable to many in their own party and also to the other party.
And almost unique in history, the front runners for the dems and repubs have very high negatives within and without their own party. In my case, as a dem, Hillary is not my first, second, or even third choice, and hence I might be tempted to vote Repub if I had a choice like Hagel over the Hillary I don't want. In the case of Giuliani, his pro choice stand could make him totally unacceptable to many pro lifers and many think of him as a 23.99 carat phony.
So adding the choice of U for unacceptable might add some to the value of a poll. And as usual, I will likely be reduced to a 2008 choice of voting for the lesser of two evil with all the complex hold your nose and vote vomit emotion that goes with it entails.