Other
Sometimes I will write something, reread it and decide it's too snarky, so I delete it.
Sometimes I hit post and the whole damn thing disappears and I don't bother to rewrite it. (it was probably too snarky anyways..

)
All the good comments have already been made.
I'm not knowledgable enough on the topic to post, but I read and learn.
Sometimes I will not comment because of the subject matter.
Sometimes I just want to read, I may come back and comment, or not.
Sometimes I'm too lazy to comment.
I may be tipsy when I comment, but I'm very rarely drunk, and if I was, I wouldn't be able to comment.