Switching to Obama after voting Republican in 2008 seeing the disaster that 0 has been completely defies any sort of common sense.
Exactly.
These are the same kind of people forever calling up CSPAN-type talk shows with lines like, "I'm a life-long Republican, but I just learned that __________ [name Republican candidate] favors the rich, so I'm switching to Obama.".
Party affiliations reported to pollsters, and who people claim they voted for in the previous election, are both highly variable, depending on emotions of the moment.
For example, when Obama's popularity was at its peak, far more people claimed to pollsters they had voted for him than actually did.
Today the emotion seems to be mostly in the other direction.