What is meta? ×  This is a variation of this feature suggestion.
It is much more difficult to implement, but is much more
refined, as it allows the deletion of specific parts of a
comment thread.  Many - but not all - conversations in comments
lose their value after the conversation has been concluded -
fixed typos, requests for clarification etc. Conversely, there
are some conversations that are worth preserving because they
add value to the question or clarify a common misconception.
Robert suggests that moderators should as a rule weed out
outdated comment threads. While that would probably work most of
the time, I fear that judging what can be deleted and what
shouldn't often requires domain knowledge, and experience with
the issue at hand.  Therefore, cleaning up comments should be in
the hands of the people best suited to decide whether a
conversation has lasting value: Those who are having it.  To do
this, I would like to suggest the following functionality.  Add
a "recycling" symbol underneath each c