There are so many variables on where someone's thinking could be biased or incomplete that if one is going to take these questions seriously, I think a heuristic approach would be most helpful rather than seeing if someone independently comes to your conclusion.

Off the top of my head I would give points for trying to falsify themselves, taking into account human bias (if they already had knowledge of the literature on bias), asking clarifying questions instead of going with an incomplete interpretation of the problem, a willingness to be criticized when the criticism is correct, and a willingness to brush badly constructed criticism as side.