I have noticed a few incorrect "not an answer" and "very low quality" flags, which I have declined with this message:
flags should not be used to indicate technical inaccuracies, or an altogether wrong answer
Both flags' descriptions are a bit misleading and have been misunderstood and abused across the network. The (canned) response is also a tad confusing, it tells you what not to do, but not what to do (spoiler: downvote!).
The problem with both flags is that they are (ab)used to ask the moderators to judge the technical accuracy, premise, or arguments presented in the answer. That, however, is not what moderators are for, this is a job for the community. We are not arbiters of correctness, you can't expect us to be able, or willing, to judge the technical merit of potentially every post on the site.
Our role, when it comes to posts, is limited to judging whether a post fits the site's guidelines and policies. If it does, but also happens to be wrong, then all we can do is... downvote it. If, for example, the post is offensive, or spam, or an one liner without any explanation, then, yes, we will put our moderator hat on. But for everything else, we are regular users like everyone else.
I hope all that is clear, but the question remains: What are these two weird flags for?