Did you delete some negative-scoring comments? Deleting a comment does not make its influence on your score go away. If you have never deleted a negatively voted comment then I don't know why you don't have positive karma.
In the past, I have deleted negative scoring comments (long story but notice some of the odd scoring on some of my older posts). I have not deleted any at all recently.
It was my understanding, however, that karma never dropped below zero. Is what you're saying that you build up a buffer where it will never go above zero either until all of your past negativity is paid off (which I would call going below zero but not being displayed as below zero -- but that just semantics obviously)?
Someone take a look at my score and my history and explain my zero karma.
My understanding was that karma never dropped below zero.
Apparently, it never *displays* below zero but if it is deep-sixed, it might be a long, long time coming back.