As the dangerous question brought up, this stack exchange site is in a unique position because there is much more risk associated with our topics than other sites. If an answer is misinformed and provides advice that might actually be dangerous, there should be some way to remove it, for the safety of our readers.
The obvious answer might seem like "let the community decide," the idea being that people will vote on answers and "wrong" ones will be pushed down. However, I've seen it happen a number of times where poorly researched or inexperienced answers are voted up -- presumably by people who though "oh, I didn't know that, thanks!" -- because they used pictures or bullet points or relied on some outdated "conventional wisdom."
This reinforces the wrong answer and makes it potentially even more dangerous for readers.
I'm not sure what the best option is. Maybe just flagging an answer for moderator attention with a comment denoting its inaccuracy? Other ideas?