To correctly measure the quality of an item one needs to take something like Google's PageRank algorithm and apply it to people. That is, there needs to be some measure of the reputation of the person posting. This doesn't mean that a person who was correct in the past is necessarily correct right now, but it is true that people who are often correct tend to go on being correct, and people who are often wrong tend to go on being wrong. Careful people tend to continue to be careful, and sloppy people tend to continue to be sloppy. It's important to capture that reality and use it as a weight given to any particular answer.
