I welcome comments that add other perspectives especially those that actively disagree with me in a vigorous way. However, I don't allow negative comments about people. There are plenty of places on the Internet for you to express those opinions.  

If a response to your comment must either be defensive or explain how offensive your comment is, I just delete your comment and block you from further participation.  

As long as you stick to discussing issues and products, no problem, but as soon as it gets personal -- goodbye, and there are no appeals.  

Another thing I don't like is talking about me in the third person in the comments. Think of a comment here as a Letter to the Editor, and on this blog, the editor is me. If you're talking about me to someone else, either take it offline or skip it. 

Update: If a comment is sarcastic or devoid of information or ideas, especially if it is anonymous -- I delete that too. There's no point blocking anonymous people, for obvious reasons. You think someone is talking gibberish but you don't have the guts to put your name on it -- why should anyone care?