What do to when comments become discussion?

Question

I've noticed a trend on Programmers.SE, along with some other sites in the network, where a comment offering suggestions or critique to an answer often results in the answer's author spending a comment arguing the premise of the suggestion, rather than responding constructively or at least minimally.

The typical example would something as follows:

1. Adam writes a question "Do CPU's handle bytes or just bits?".
2. Barry writes a answer with room for improvement, perhaps in the form of a sonnet.
3. Charles comments with a suggestion, such as "maybe don't write as a sonnet."
4. Barry replies to Charles comment defending his choice, often with a "you should read my sonnet" line.

What should everyone do here? Should C and B have a multi-part discussion in their comments? Should B's "read my sonnet" line be flagged, by either A, C, or D ("Dave", who was just reading.). Should C delete his comment and try to re-state?

Answer 1

Aside from the relative merit of using sonnets to answer a question, the guiding principle is this:

Comments are for clarifying questions and answers, or asking for clarification. Any other use makes them subject to removal.

If the comments are anything but that, cast a flag against them, and a moderator will remove them if they are onerous. The key on any Stack Exchange site is to reduce the noise as much as possible. This is already done by the system collapsing long strings of comments, but if the comment thread has become particularly noisy, a moderator can take care of that.

For some comment conversations, a "would you like to move this conversation to chat" link is offered. Chat is more relaxed about these things; if you want to discuss the relative merits of answering Stack Exchange questions via sonnet, by all means avail yourself of the chat facility.

Further Reading
How do Comments Work? (Meta FAQ)
How to Use the Comment Privilege (from the Help Center)