Can't really speculate too much why it was handled bad without knowing the exact context. Though, it was likely accidental or the reason you specified in the report field, the mod might disagree with, however ultimately decided to remove it for another reason. Generally though, I tend to mark these good, unless they're completely off the mark. This will always differ from moderator to moderator, because some users will want to know exactly when they've included a bad report message, and not just reporting a post that should be removed, therefore a moderator could prioritise the message, instead of the actual report if that makes sense.
For example, if you reported a post for plagiarism, and included "plagiarism" in the report field, upon reviewing it if the moderator disagrees that's plagiarism, they may mark it bad, even if they think it should be removed for another reason e.g low quality.
Do you know that from experience or do you just assume it should be like that? Inaccurate information that stimulates a completely illogical and unnecessary discussion is definitely something I report, but always with evidence that confirms it.
There's no one answer for this, because it absolutely depends on the context. For example, if the post is clearly trolling, then that could be a reason for removable, however simply spreading misinformation isn't exactly a reason for removal, depending on the context. Since, the forum generally likes to keep freedom of speech. Though, absolutely the community are free to outline why a user is wrong, and let others know that they're spreading misinformation.
Therefore, often you'll find that the action taken on these types of reports will be highly dependent on the moderator who is handling it, and could potentially differ widely between moderators. This is also some of the examples I believe in setting guidelines, and not strict rule sets, since the a lot of the time they can overlap each other.