You can't ask the question of whether certain statements, to the people giving them, are matters of fact or political opinion, and then have "correct" answers which are provided by others. If you have correct answers, you already know that certain opinions are based on error. The only thing you can do with such an experiment is measure how well people can guess what the judges think to be true. As it turns out, they did fairly well.
I could care less about this example, but let's take the WMD question. Old WMD was found in Iraq. http://en.wikipedia.org/wiki/Iraq_and_weapons_of_mass_destru...
A partisan wouldn't argue the facts. He'd simply point out that, depending on how you phrase the question, the answer could be interpreted either way. The questioner has to rephrase "After the second Gulf War, were WMD found that were created in between the two wars?"
This easily goes to extremes, and questions end up being extremely detailed in order to resolve matters of "fact" This is why the role of fact-checker is a waste of time. Most all of the time, politicians aren't lying, they're simply phrasing things in enough ambiguity to create the desired impression. (This actually works for me as "bullshit", but it's not lying, and it's not giving out factual errors)