What is the best way to go about posting an informational question when there are existing near-duplicate questions but they do not contain keywords essential to people searching for the information?
Stackoverflow (and to a lesser degree, the rest of stack exchange) have stunning SEO. When I have a problem and a stackoverflow post is the first result, there is a good chance there is a solution I am seeking in concise form. Thus, when I have a problem but find no stack overflow posts in the Google results, I sometimes create a question even when I've already found the answer so that future Googlers (often myself several months later) are not left with the same desert of search results.
Recently, one of these questions got down-voted for being a near duplicate of another question. Gaping dissimilarities between the two questions aside, nothing appeared in my searches for this problem. My question now appears as the first Google result for my old search, but the question and answer are littered with discussion of duplication and this detracts from the essential point. Thus the question above. What does one do when existing questions on a topic are bad enough in SEO that they they may as well be different questions even if they deal in the same content? In particular, what if these questions have bad enough SEO that you don't even know they exist until people rail on your question for "redundancy"?
As an added thought, what if there are several disparate questions on a similar theme and you want to have a single question that addresses them all? For example, a question about databases where there are answered questions for specific databases that are fairly similar but none asking the question in general.