What determines the flags that are available when one is flagging a question?

Question

Sometimes there are only three basic flags available:

• spam
• rude or abusive
• in need of moderator intervention

Sometimes there are additional flag options in the list, such as:

• very low quality

What determines the flag options in the list? At times, I would like to flag something "very low quality", but it is not available, and I'm not sure if I should be using "in need of moderator attention" and specifying "very low quality" (or words to that effect), in the description.

Is it that someone else has already flagged it with that flag, and I just can't see it and it is unavailable after someone has already used that flag? Or, is it something automatically determined, based on the text of the question?

I checked to see if the following might be related, but the questions do not have positive scores, and refreshing does not show up a hold/close, etc:

• Flagging question options seems to have shrunk
• Where did my flag options go?

One additional thing I have observed is that the question seems to have been "favourited" by someone. (Although, as I mentioned, it does not have a positive score.)

I have noticed this on SO, but I suspect that it may be widely applicable to all SE sites. I want to avoid using flagging improperly.

Answer 1

You won't be able to flag as very low quality if the question is already in the close review queue.

Very Low Quality won't be available for questions that are currently undergoing Close review either.

^{Source: Disputed flags and triage}

As the question is already in the close review queue, there's no point flagging it as very low quality.

The idea is that the function of the "very low quality" flag on questions is evolving to act as a way of finding things that review didn't catch. Once something is under review, there's no need to indicate that it needs to be reviewed. Spam, gibberish, etc. are addressed by the remaining flags.

^{Source: Missing "VLQ" flag option in Triage Queue}

This is in addition to the other times that VLQ flag is disabled: if the post has a positive score, or if it's already closed or deleted.

On Stack Overflow only, the VLQ flag won't show if the question is in the Triage review queue:

Very Low Quality won't be an option from within Triage review or from anywhere else while a question is being triaged.