To LittleHawk's point.
When Hillary explains her position about the Iraq invasion, she cannot admit to her mistakes and that's a bad thing.
When Obama chides her for it, he says he won't make mistakes and that's a good thing.
Twisted logic.
We all make mistakes and if you continue to give this man a free pass you will be making one.
You must test him.
But as the man said "The opinion they already have about the candidate profoundly influences their evaluation of the candidate's behaviour."

That is a hurdle that most of us never clear.