I think it's entirely valid to not add karma to a comment you agree because it's reached the karma you feel it deserves. Similarly as people have pointed out y

I think it's entirely valid to not add karma to a comment you agree because it's reached the karma you feel it deserves. Similarly as people have pointed out you don't need pile on the down-modding simply because you don't agree with something. I would almost say that unless something is actually disinformation, spam or trolling you shouldn't down-mod it, even if you disagree. Upvote the comments you agree with or write a persuasive argument instead. One thing that I like about Stackoverflow.com is the ability to see how much people down/up mod.