It is no secret that certain tags attract very basic questions which are easily answered by even a novice. regex and php come immediately to mind. Many of these questions are quickly closed as they do not represent useful content and, in the opinion of the community, will only degrade the quality of Stack Overflow.
Some users, however, answer these questions anyway. Some questions are, perhaps, borderline, while some users don't compeletely subscribe to Stack Overflow's concept of "on topic". Some users, however, know that these questions are of poor quality but are using them specifically to gain rep. You can spot them if you pay attention: repeating themselves, sometimes multiple times a day (occasionally even copy-pasting an answer), in attempt (I believe) to rapidly gain rep.
In the past 12 months (from 2013-01-01 to the time of this posting), 33,851 users have gained 2 rep or more from a post closed within 24 hours of being created, for a total of 2,165,414 reputation points. 38 users have earned over 3,000 rep on these kinds of questions alone.
Why is this a problem?
I don't begrudge users who make it their business to answer every question on the site and who aren't terribly concerned about quality standards. I think they should be welcomed, for the most part, because, in their own way, they are trying to make the world a better place. In fact, Jon Skeet comes in at #1 from most rep earned on questions closed within 24 hours of creation. I've even answered a question or two because it was interesting, even though I knew it'd probably be closed.
But I don't think they (or I) should be earning reputation for those answers.
Reputation grants a user the ability to "do things" on the site (what else is it good for?). Privelges are associated with rep because rep is supposed to represent experience with the site. Allowing users to earn rep from questions that the community has decided don't belong here seems counter-productive. Since there's a delay between asking a question and closing it, some users are "gaming" the system by slinging off quick answers in an attempt to earn at least an upvote or two and maybe the much coveted "accept". I've seen multiple examples of users posting a stub "Answer is coming..." to get their foot in the door on a question they know will be closed. Of course, not all (or even most) of these users have nefarious intentions, but they are still gaining rep and priveleges for using the site in a way that the community has deemed unhelpful.
Downvoting answers to closed questions (as "not useful") doesn't fit our model. Neither would it be effective, as it would take 13 downvotes to "balance" a single upvote and "accept" from the OP.
I propose that reputation earned on answers to questions closed within 24 hours for any reason except "duplicate" be neutralized.
Why exclude duplicates?
Duplicates are a bit different from other questions. While off-topic, primarily opinion-based, etc, indicate that there's a problem with the question in and of itself, duplicates indicate that there's a problem with the question in the context of all other question asked on the site.
A user could easily read a question, recognize it as on-topic and answer it, not realizing that it'd been asked before (perhaps only once, with a significantly different title). Also, the answers to duplicates may, in many situations, provide additional information which is not included in answers to the "other question". Therefore, I think questions closed as duplicates should be excluded from neutralization.
Why 24 hours?
For question asked and closed in 2013, about 80% were closed within 24 hours of creation. The rest quickly tail off into days, weeks and months. A question which is not obviously off-topic (etc) will, naturally, take longer to attract the necessary close votes. If a question is not obviously off-topic, then users are clearly acting in good faith to answer questions and shouldn't be penalized because 5 other users who happened across it over the course of a week thought differently.
Standards change. Questions which were once on-topic can become off-topic. Reputation earned in the past, and which has been cemented by a (relatively) long history, should not be taken away. Reputation on answers should only be neutralized if the question is off-topic according to the standards that day.
I could see one exception to the 24 hour rule: if the question is closed by a moderator, then perhaps neutralization should still occur. I hesitate to suggest this, however, because I'm not sure what the unintended consequences might be.
What About Reopening?
If a question is reopened, I see no problem with reputation being restored to answerers. Sometimes questions are closed in error (due to the Meta effect, etc), and users who've answered the question in good faith should have their rep restored.
Should this be Retroactive?
No, I don't think so. Seeing a giant drop in reputation all at once would not be the point of this proposal. The point is not to neutralize user priveleges McBain style, but to gently encourage users to stop pursuing these types questions for the rep.
What's the Goal?
My hope would be that users who are answering poor quality questions in bad faith (desiring only to earn reputation) would become discouraged over time and stop answering questions they know will be closed.
New users who don't understand the rules won't be greatly impacted because, in my opinion, they shouldn't be earning privelges for those answers anyway. Active users who make a point of answering nearly all questions will be somehwat affected, but not much. The average user earned only about 60 rep on these questions over the course of the entire last year (counting the handful of answers which earned net 0 or negative rep for the user) - not enough to cause any great harm if neutralized. Jon Skeet would be the biggest loser, at just under 12,000 points. (Again, though, this proposal would not be retroactive.)
Only users who are specifically pursuing these kinds of questions are going to feel any real sting from this proposal.
Yes, [discouraging users from answering questions which might be closed] is the goal here, to ensure that people are only providing answers to quality questions, and not answering low quality questions. Low quality questions are much more likely to result in low quality answers, be less discoverable, and not be helpful to other users. If people spend less time answering poor quality questions and spend that time instead on higher quality questions then this would have been a successful change. If it means that people asking questions need to learn to ask quality questions to get an answer instead of asking a bad question, then great.