(2) probably would not work. Commenters could troll, and then the community replying in disagreement would up-vote their comment.

Here are my ideas: (A)Not showing someone their karma score ever, unless it is negative.

(B)Leaving a line between the comment field and the reply button saying, "Stay constructive."

(C)That line of text could link to the guidelines.

(D)Detect if someone says 'idiot' and then change the line to, "You said 'idiot', do you still want to post?"