The comment thread on Joseph's answer is getting a little long and there's an extension of Joseph's proposal in there that I'd like to draw to everyone's attention. The full proposal is:
- Experienced user spots an "answer" that isn't really an answer.
- Experienced user leaves a helpful comment explaining what best to do with that answer.
- Experienced user flags the answer for moderator attention.
- Assuming that the moderator agrees, the moderator then leaves a comment whose content is designed to indicate that Experienced User was acting in accordance with the site etiquette and that after X days, this answer will be deleted.
- After X days, the answer is deleted.
Note: nothing prevents anyone reposting the "answer" themselves as a comment or question if they decide that it is something that they themselves would have said or asked if only they'd thought of it first.
I also suggest that there be a basic template that can be used for the comments. This can be ignored, but I find it helps to have something to fall back on. It should be polite and it should indicate why it is in the best interests of the original poster to repost their answer as a comment or a question. Here's my proposals:
Experienced user's comment (on something that should be a question):
Hi, welcome to tex.SX. Your question won't get seen by many people here so it would be best to repost it as a fresh question. Follow-up questions like this are more than welcome! Please use the "Ask Question" link for your new question; there you can link to this question to provide the background.
Moderator's comment (on something that should be a question):
Just a note to confirm _X_'s comment, this ought to be reposted as a question for you to get the best chance of it being answered. Also, it's a little confusing to have fresh questions in the _answers_ section, so this answer will be removed from public view in _N_ days.
(I said "removed from public view" rather than "deleted" deliberately, others may think I'm being overly polite there!)
If the "answer" should best be left as a comment then there's the problem of reputation. If it's the poster's own question then the above can be adapted, but if it's a different question then the poster may not have the reputation to comment, in which case I would say that the automatic deletion be put on hold until the comment is either irrelevant or the user has enough reputation to repost as a comment. If the comment is particularly pertinent, the "Experienced User" could post it (with correct attribution).
(CW so that anyone can edit the comments, and propose modifications for separate cases. My idea is that these be easily cut-and-pasted with only minor editing to make it easy for all to do.)