A while ago a question was deleted for which I had spent quite a while doing the research to answer it correctly. The reason for its deletion appears to be that most people didn't think enough information was present in the question. There was not; but it was still possible to give the case in which the answer to a question within the question was true. The Author wanted to know why this was the case.
Link to Question: https://math.stackexchange.com/questions/2079036/if-Γ
The question was as follows: If A ⊨ B and C ⊨ B, then A ∩ C ⊨ B is false? Why? Propositional logic
My Answer: The third statement would only be false for the case in which the set of interpretations that make all members of A true does not have an intersection with the set of interpretations that makes all members of B true.
Giving the answer to the cases in which the statement in question was false would have allowed the author to look more closely at his/her text and perhaps edit/answer the question.
Because the question was updated almost directly after the first few comments we can observe that the Author was furiously re-reading the text and thinking of ways to re-write the question. This all happened while the question was reviving down-votes: which must have felt rather bad for the Author.
I believe the question was closed prematurely. Either by the Author or by some auto-delete function of the site that I am not aware of.
In principal, I do not believe questions should be closed or criticized before the Author of them has had time to update the question based on feedback they receive in the comments.
I would also like to link here: http://meta.math.stackexchange.com/questions/320/how-should-we-deal-with-ill-founded-questions
For the comment made by Akhil Mathew:
I'd say answering in the comments is best. If the question was well-thought out and well-written, I'm sympathetic; in this case, since there is no motivation for the question, my inclination is to close it.
I agree with Mathew's comment; however one should note that not everyone has the privilege to answer in comments; which might allow people to clarify certain points in the question and perhaps direct them to a better one. Those that do not have this privilege run the risk of losing what little rep they have with a bad answer; which results in long research times to ensure what they say is clear and not false. In my case the time I took to do this exceed the life of the question.
I propose that questions should not be deleted by a party other than the Author within a certain time frame of creation particularly if the question has been edited or is still been edited.