I recently gave a really bad answer to a question, it was so bad I thought 'I wish I hadn't have said that' and started looking for ways to delete it. It didn't take me too long to find the delete button, at which point I thought, I bet there are other bad answers of mine with no value to the site I could delete.
In this case my thought process was a purely selfish one (not wanting to look daft) but as I filter through questions and answer which are useful to me at any given point I often think there must be ways to reduce this noise (bad questions and answers) for the good of the community.
If I had been aware that it is a good idea to delete bad answers (questions as well although it becomes trickier in this case and people seem more willing to vote to close questions) then I would have done it earlier. My question is why not flash a tip to users when there answers are getting down voted to an oblivion which would suggest a deletion, the primary goal being to help remove noise from the site.