Each kind of karma point would be aligned along it's own axis in N-Dimensional space. The resulting total karma score would be expressible as an N-dimensional manifold. You could then filter the resultant N-ary manifolds using your own total karma manifold. The results would be utterly transparent to you... instead as you accumulate karma points it informs the shape of your own manifold that is being projected onto the comment moderation system results.
In short you would experience the Slashdot that best fits your perceptions of reality.