It's too easy to give a glib answer, and feel justified because you're right.

I work hard to post helpful, constructive, conversation-advancing remarks instead. I fail regularly. But sometimes I get it right.

Some simple moves I make to help me be more positive:

   Remove the word 'you' from my comment. It's rarely helpful to put words in someone's mouth, or deconstruct another comment. I try to limit my comments to my own ideas. It's so very easy for others to read 'you did blah' and feel indignant. I don't want to generate that. Looking for the word 'you' in my post is a red flag that the post isn't advancing the topic.

   Accept criticisms, and respond in a meta way if at all. Getting bogged down in a dictionary definition or arguing who's statistic is more pertinent is low-leverage discussion. 

   Ask questions as often as making declarative statements. Offer new information and ask if it helps illuminate the topic. That adds something, opens the way for further dialog, and admits a topic may be more nuanced.

Anyway, thanks to those that helped me understand that winning karma points is not the real point.