It's more useful on help boards. If someone posts a question and then I answer it, they might raise my reputation - because I was helpful - or lower it, because I was an ---. Other people could also then come along and say "wow! he was helpful!" and raise my reputation, or "what an ---!" and lower it. The amount of reputation YOU have determines how much you raise or lower others' reputation.
See? Stupid. It's every silly karma hack that no one has ever used.
See? Stupid. It's every silly karma hack that no one has ever used.