1. Auto DM's
The junk mail of twitter. This pointless, generic one size fits all crap makes me want to unfollow everyone who sends it. I began following you because I had personal interest in you, your posts, your company or your life. Visit my profile, check out my blog, review my posts and decide if you feel the same. If you do follow me, maybe send me a DM to talk about shared interests or direct me to someone or something you think I would appreciate. Don't Auto-DM me. Actually I am going to go an unfollow every Auto DM I received right now.
2. Get Rich Quick Schemes
I have a career. I have some money. My dreams are bigger than crap like scrapbook software to stay-at-home Mom's, boring Aunt's and people who don't realize Facebook is the easier, more interesting and the scrapbook of the future. I am also not interested in setting up my own shitty .com scam, a ponzie scheme or becoming apart of Amway. Get a life, get a real job, leave me alone. Ohh, and I probably unfollowed all of you after my post above.
3. People with no friends
You've seen them on Twitter. People who in real life have no friends but they seek acceptance by following 34, 568 people that they have nothing in common with knowing 22,346 of them will follow back. This makes them feel popular. This makes me unfollow them.
At the same time there are plenty of reasons I like it. Lucky for you Twitter ;)