Also, I believe that deleting a comment does not dissipate any negative karma that it has already earned you.

This is correct.

I do not delete to avoid the karma hit, I delete to drop the number of comments in a thread. If two other people say the same thing there was no reason for me to say it.

In this case, I realized immediately after I posted the comment that I probably had not done justice to the entire thread, so I deleted it. I find the clutter annoying and if I can voluntarily take my comment out of the path I am happy to do so.

Unfortunately, this apparently does not work because two people have responded before I could delete a comment. So, deleting does not work well and now I know. Next strategy to try, just editing with a sentence saying "Ignore me"? What is the community consensus on this subject? Just leave the comment alone?

It would be neat if there was a way to just hit my own comment with -4 and get it off of people's radar.