So many times I've come across questions where the OP has wrote a lot of text describing the issue they are having, but haven't provided any source code. And without the source code its almost impossible to answer their question without guessing.
Should I be flagging these questions? If so, under which category?
I only ask as I'm tired of commenting "Please provide source code" on every question.
You can keep leaving a comment or vote to close. The only thing moderators can really do is close it faster, but this doesn't seem like an exceptional case.
I bring warnings of a future with zero flag weight, cold and alone if one pursues a general "no code, I flag" policy.
Ok, in less Dickensian fashion:
If it helps, I personally "vote to close first and ask questions later". The basic concept behind that is closure is not deletion. If the OP improves their post, it'll either not be closed, or re-opened as needed.
As to the flag itself:
Very low quality: so poor closing it doesn't do it justice. The description says severe content or formatting issues. As in, if you see this posted somewhere:
uhfweyr78yeo89yreojfj08y4wdw
That is very low quality. Slightly extreme, but you see what I mean: very low quality == totally unintelligible. So in this case, it's not that the question is unintelligible, we just might not have the means to answer it. In which case it is "not a real question".
Source code is not a requirement for posting a question on Stack Overflow. There are a number of on-topic questions that don't require it.
I often request an sscce— a Short, Self Contained, Correct (Compilable), Example—especially in a GUI context. It has the salutary effect focusing on the problem and eliminating irrelevancies. It can help turn a "Debug my (wall of | unseen) code" questions into a "How do I implement this feature" question. It was designed by a respected contributor in the Java arena, but the concept has grown to see much wider use.
If there is a reason to close it, then you should vote to close the question (or flag the question to be closed); the fact the question doesn't show code is not a reason to close it, but if the question is not answerable in its current form, then you can vote to close it as "not a real question," if it is not possible to understand what being asked; as "not constructive," if the question is asking an opinion, or would generate debates; as "too localized," if the question would not help any future users.
Apart the case of the question being spam, offensive, or containing hate speech, I don't see other reason to flag a question. I would not flag it as "very low quality," as that would just move the task to somebody else (the moderators) who could not do something more than a user could do; they could eventually close the question, but so far I have not seen a question being closed for being low quality. If the question's quality is low, and you can edit it, you should edit it; if the question's quality is very low, and it is not possible to understand what being asked, you could down-vote it. In any case, you should not flag a question for moderation attention, when there is something you can do.
Moderators are human exception handlers, and you should not invoke their action just because you don't like the question.
My opinion is that if the question needs some source code for you to be able to answer it but it does not yet, then ask yourself "Is this question worth saving?" - that could mean that the question is strong but the user may have just not realised source code would help (maybe a new user) - in this case I would recommend commenting and asking for source code.
If the question is fairly useless anyway, and even adding source code would likely help any further visitors to the site then I might opt for the "vote to close" button and just leave it at that.
The dilemma of course being, what if you comment and ask for source code, but the user never bothers to add any - without source code some questions need to be closed... how long does one "monitor" a question in await for source code before voting to close?
...maybe it would be good to flag questions for personal monitoring (assuming this doesn't exist already - and I don't think "favourite" is an option for this)
Flag it as Very low quality. If the code is not legible, then it is has very low quality...
