Recently, a couple of invalid answers have been flagged as NAA. This is somewhat of a duplicate of this answer on our policy, but I want to mention this because it's important that everyone is using SE's tools correctly (I know, a bit atypical for our site) to make sure things happen as they should and to make our job easier.
Here's how you should be using flags:
- if a post is obvious spam, flag it as spam
- if a post is rude or abusive, flag it as rude or abusive
- if a post has severe formatting issues or is just unsalvageably low-quality, flag it as very low quality. if you can fix the formatting by editing, edit / suggest an edit instead
- if a post doesn't attempt to solve the problem at all (including answers that should be comments, irrelevant but not spam/rude remarks, etc), flag it as not an answer
- if the post is an attempt, is formatted fine, but is invalid because it doesn't properly complete the task, leave a comment letting the answerer know so they can fix it, and if they still haven't fixed it after a day or two, flag it for moderator intervention
This is important for two reasons. Firstly, NAA flags send the post to the VLQ review queue. If it's an attempt and its formatting isn't terrible, this will likely be reviewed as "Looks OK", which then dismisses the flag as disputed. Basically, an invalid answer is still an answer, and unless it's blatantly obvious it isn't valid (like if the answer itself says it isn't 100% correct), it'll probably be accepted in the review queues. Normal users can't see that it was sent there by a flag, so they will probably assume it's just a mistake by the system.
Secondly, NAA and VLQ flags won't show up to moderators for an hour, to give the flag time to be resolved through review queues by the community. This means that unless one of us is checking the review queues or refreshing the flags page and ignoring this time filter, we won't actually be notified of your flag for a full hour, during which time it could get disputed by a review task completion.
TL;DR: spam, rude, VLQ, and NAA flags are fairly self-explanatory. However, if an answer is a legitimate attempt that doesn't have content issues, but its only issue is it doesn't actually properly solve the challenge, leave a comment and later (48 hours is a good guideline), flag it for moderator intervention. This immediately sends the flag to our inbox and doesn't put it in the review queues.