Although false-reporting is technically a violation of the Code of Conduct, there isn't actually a way to report people for this. The only way people can receive a notification from the administration for false reporting is by reporting various posts/comments without adding a reason. In some communities people call false reporters other names. For example, in the Steel Diver: Sub Wars community, people call false reporters "bansharks."
False Reporting is when someone reports a post even though it didn't break the Code of Conduct.
For instance, if you say, "I love zelda!" in the Zelda series community, and you get a notification from the admins that says it was deleted for hateful and bullying content, you were likely false reported.
Not all posts on Miiverse are reported and deleted falsely. Everything that is listed as a Violation in the Miiverse Code of Conduct can be legitimately reported. This means spam, personal information, profanity, violence, sexual content, references to criminal activity, hateful, sexual, religious and political content, false reporting (even though most false reporters get away with it), advertising and impersonators.
To expound, in the Miiverse CoC, under "Violation Types," there is one that says "Other." It lists several violations that do not fall under the normal categories. One of them says, "Content that disrupts the community: repeat posts, completely blank/ all black posts, meaningless scribbles, etc."
It is a mystery whether off topic posting is against the CoC, as many off topic posts, have been left un-touched even though the CoC states off topic posting is a violation.