I wouldn't say it's a terrible quiz. It's pretty good for a quick quiz. I did the same thing you did, put in my answers to all the questions, and then tried each different answer for the question regarding drugs:
No = Libertarian
Maybe = Libertarian
Yes = Libertarian
It depends on the combination of answers to the questions where that little dot lands on the graph... since I am heavily libertarian (I don't see human beings, myself included, as state property) the changing of my answer to one question didn't cause the red dot to move out of the libertarian "zone" on the graph. However if the combination of your answers result in your dot being on a line then the changing of one answer would result in your dot moving accross the line, which makes sense.
So anyway, what was your actual answer to the drug question?