The close vote queue is a goldmine of information, so let's embrace it
While I tend to agree with those who suggest that it should just be flushed, I also have to say that this discussion is going in circles, and a fresh approach to the queue is needed.
The ideal meaning of a close vote is that a community member has analysed a question, found a specific problem with it and taken the trouble to vote to close it.
This is also how close votes work for many (most?) questions, where people see the question in the queue, do their own "analysis" and agree with the original voter and add their vote to the tally. Unless, of course, they disagree and vote to save the question from the queue.
However, the questions in question stay in the queue because they have been around for a few days without four good men and women having added their vote to the close process. After that time, they are so far down the queue that practically nobody will see them again in the context of a close vote review. They will linger there forever, unless they somehow reach 100 views so their accumulated votes start to decay.
What does this mean?
Given how the queue works, the questions they contain have in reality been reviewed by the community (or a small part of it, but that's how the queues work) and deemed to be... meh.
Or another way to put it: the questions in the close vote queue have been weighed and found to be not bad enough to waste time and a close vote on, but not good enough to save, either.
Now, this is some real information about the quality of the question.
The quality assessment information provided by the community
If we accept this source of information, we have the following quality information for ranking purposes:
- Up- or downvotes
- Lingering close votes
- Actually closed questions
- Deleted questions
There may be a few more that I have missed, so please feel free to suggest them in the comments.
And before you dismiss this analysis totally, please notice that I am aware that "quality" is a loaded word, and in the above I have used it in the broadest sense. A closed question is not inherently a bad one (it may for instance simply be off-topic,) but relevance is also a quality, so I don't see a problem in using the information for ranking purposes.
It should also be considered that the close-voting process has a certain tediousness to it, as it takes at least 3 clicks to vote to close a question, as opposed to a single click for a downvote. Therefore, a close vote could easily be considered on a par with a downvote in the quality rankings, maybe even more.
With this approach, the much criticised close vote queue changes from being a source of frustration (i.e., a liability) to become a source of information in the quality ranking of the posts on the site, and hence a real asset.