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.

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 left 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.