I had not given this question enough thought before asking it. I went straight to looking for a reference without thinking about it. Somebody pointed out the obvious solution in a comment. Should I delete the question or give the commenter the chance to turn this into an answer (and earn reputation) ?
To answer the comment question, "Why not just answer the question instead of discussing in comments?", my belief is that your question is both too general and too specific for meta. The specific question for meta was your question above, and (except for one snag), the specific meta question has served its purpose and could be deleted too. The general question, how to decide, is a good question to which there is no good answer. The community may decide a question should be closed if it does not meet certain criteria, but aside from not being spam or unfriendly, there are no rigid technical criteria.
In short, there is no good answer to the question. It really depends on many factors, not just the content of the question.
Gerhard "This Answer Is A Snag" Paseman, 2015.08.31