As with any public content system, there's no guarantee on the quality of initially entered questions. Hopefully the voting system will mean over time the overall quality will increase, and will help people who have had content removed to write better questions.

That being said, if you see a question that's incorrect, and the comments don't justify it, then feel free to vote it down. Once it has enough down votes it will be hidden from the site anyway.

I'm actually thinking at some point in the future, of removing out voted questions from your past exam scores, so your averages won't be affected by bad questions in the long run. I haven't exactly figured out how this will work, but it's on the road map.

Maybe you could add a few questions to the pool to help out?