Not to be a copycat OR negative, but I was just reading "A Brief and Informal Twitter Etiquette Guide" (http://www.chrisbrogan.com/a-brief-and-informal-twitter-etiquette-guide/) and had some thoughts of my own to share. Here are some truly annoying things people do in Twitter that lead me to want to unfollow them:
1. Overuse the "@" or "RT" function
2. Share a very sparse thought like "I was..." with no ending to the thought
3. Speculate about things very self indulgently, as in "Just thinking..." - obviously you were just thinking, you're posting that thought on Twitter!
There are other annoying things I'm sure, but nothing that comes to mind very immediately. Here are a couple of GOOD things to do:
1. Provide useful information, tips, etc.
2. Share breaking news
3. Share a good quote. I really enjoy that.