I have used very low quality flag for this question - was accepted.
Your flag on that question was implicitly accepted after the question was closed by 5 regular community members. There was no moderator intervention, neither to close the question nor to review your flag.
However, I agree that this flag was valid. That question is terrible and really should have been caught by the automatic quality filter.
But for this one - declined
You should have been told why this flag was declined, and this should appear on the same page where you're seeing "declined".
But I can guess that it was because of recent changes to how moderators handle "very low quality" flags. One of our moderators explains a recent similar case here. The summary is basically that the "very low quality" flag reason is intended for questions that are completely unsalvageable through edits, should not have been posted in the first place, and should really just be deleted. I suppose someone thought that question could conceivably be edited to bring it up to our standards, making it a valid question.
To be honest, I question this assumption, if that was in fact the thinking of the moderator who processed your flag. That doesn't look like a valid question to me, and it doesn't look salvageable. A[nother] moderator even agreed that it was off-topic and needed to be closed. I don't see much use in quibbling over the particular flag reason that you picked; the question is clearly problematic and in need of attention. It needs far more than a little cleanup to be acceptable. I would have marked that flag valid.
Most likely, the thinking was "this question is bad, but you shouldn't have flagged it, you should have voted to close instead". The thinking here is that the question can simply be closed by the community and doesn't require ♦ moderator intervention. That's also reasonable; consider doing so in the future.
Flag number 3: ohter: trivial question - accepted
That flag should not have been marked valid. "Trivial question" is not a valid reason to flag a question because there is nothing wrong with asking simple questions! We have lots of guidelines concerning the types of questions that should and should not be asked here, but you'll notice that none of them say anything about questions that are "simple" or "trivial". This is not just because assessing such things is subjective and entirely dependent upon an individual's perspective, but also because our goal is to build a comprehensive resource of answers to programming questions. That naturally has to include the simple ones as well as the complex ones, to whatever extent those terms have meaning.
But of course, like you point out, the flag was marked as valid. That's because a moderator took action on the question anyway, closing it as a duplicate. That action automatically caused your flag to be marked valid, even though you flagged it for an entirely different reason. The flag system isn't perfect. Mostly, we're just trying to figure out whether you're wasting our time with utterly invalid flags, or making a reasonable attempt at improving the site.
Flag number 4: very low quality - declined. For the last one the flag was declined before question was edited - it wasnt any code there...
Basically the same thing as #2.
Even with the code that's been added, I don't think this question deserves my vote to reopen it. I'd have certainly marked your flag as valid when the question was in an even worse state.
But you still should have voted to close.
There are some criteria for low quality question - but it depends more of moderator itself..
Am I right?
Yes, you're right.
There are some criteria that have been discussed here on Meta for what constitutes a "very low quality" post (for example, here), but it's hard to come up with a universal consensus. Different people have different standards, and in practice it ends up being very much like pornography—hard to exhaustively define, but you know it when you see it.
And of course there is a human element involved in processing moderator flags. The mods are, after all, humans. They even make mistakes sometimes. And they all have to use their own best judgment. Not every moderator would evaluate the same flag on the same question in the same way. Some may think that's a bug, but I think it's actually a feature. :-)
More generally, if you are unsure about whether a post is bad enough to be flagged as "very low quality", you have a couple of alternatives:
- Downvote and vote to close the question instead.
- Use the "other" flag reason and detail your concerns. Moderators pay more attention to custom flags, and you have more of an opportunity to explain yourself.
But the best alternative is really to give up worrying too much about which of your flags are being accepted or declined, and just get on with your life. Unless there's a clear pattern of repeated invalid flags, you're doing just fine.