The criteria to close posts have one common goal: improve findability of good posts / answers and prevent useless weight on the site. In some cases, you are pretty sure a post *will* become useless weight, although it does not fit 100% in one of the existing criteria.

In the case of "unclear what you are asking" that includes the situation in which a question or problem is clear, but cannot be answered without additional information. The poster however seems to have leftt the building, and does not reply on *valid* requests for additional information within a reasonable amount of time. In these cases, many times I vote to close as "unclear what you are asking", simply because you cannot split the criteria to close into a list of two pages to fit all possible (valid) reasons to close.

At the same time, to judge *if* the quality of a request for additional information is sufficient,, you need to be familiar enough with the subject to decide. If not, the review should be skipped.