Remember when SurveyUSA did their 50-state polling in March 2008 with Hillary vs. McCain and Obama vs. McCain (even then Hillary did relatively well in KY, not in this one but in other polls by SUSA from KY), while Obama did already as poorly as on election day or worse - The reverse was the case in CO with Obama doing well and Hillary not so much:
One could not have seen a significant difference between Hillary Clinton and Barack Obama in March 2008. Results of a Clinton-McCain election would have been close in electoral and popular votes to what happened because of the economic meltdown late in the campaign season.