[EricH]

Originally Posted by Molten

Red dots have been used more and more for simple disagreement.

And green dots are often used for simple agreement. I can think of reasons to give reds, but I usually don't because it's obvious that the "offenders" have already gotten plenty.

If you have a simple agreement or disagreement, there are some other ways to communicate it. Neutral rep, for instance. Or PMs.

Or you could just ignore the rep system altogether.

Edit: I'm with Joe on why I'd give any negative rep. I never have given any, though. In at least a couple of cases, I've been glad of it later. Typically, everyone else beats me to it, and I figure enough is enough.