I am very active on facebook.stackoverflow.com
and I see there many questions that are either off-topic, un-constructive or simply a request for copy/paste code samples.
My first reaction is obviously to flag and then to place a comment reminding the user what questions to ask or to be more specific, etc...
These questions are usually down-voted fairly quickly and in most cases closed and even deleted, however, many new users looking to up their rep wont hesitate to answer.
What would be the best way to discourage users from answering a question that clearly should not be answered (in its current form) ?
Update: Would it be acceptable to down-vote such answers (even if they are valid) and include a comment explaining why this question should not have been answered?