I tend to have very consistent results on every political quiz I take. Still, you can't get an unbiased quiz.
For example at Political Quiz.net they ask "Should gay marriage be legalized?" My response is no, but that is because I don't believe that our government should be involved in marriage at all, which is actually a more pro-personal freedom response than believing in gay marriage.
The questions are almost always going to show the bias of the creator.
Very hard not to show a bias. For instance, the question, "Should corporations be given government assistance," isn't neutral to some because it presupposes the existance of corporations.
This is a problem of all multiple choice questions, they must operate from a set of premeses.