The poll is a little biased. It gives the impression that people either vote or dont vote on third parties just because they are a third party. A better additional option would be "No, I haven't found one I agree with" and "No, I wont vote for third parties"----No, and I dont plan to, and no, but I plan on it imply that you either are or arent voting on them BECAUSE they are third party.
As stated before, the biggest problem with a third party is that it would split the vote. Although Im a conservative, Im aware of the problems of trying to get someone who is too conservative into office. It will split the votes because many independents will think the person would be too conservative. It is actually a problem the republicans will have in this election. The "Grass Roots" movement is a big part of the republican party, and could easily cause a Ultra Conservative to reach the primarys, however, it will polarize the votes, and although I hate to say it, almost guarantee a republican loss come election day.