I Follow because of Content, I Unfollow because of Spam. Spam adds ego to the sender but adds no value to the follower.

• Obvious commercial messages are spam
• An RT of an RT’d own tweet is spam
• Foursquare, runtastic notifications are spam
• Automatic (welcoming) notifications of (un)followers are spam
• Only “Good morning/afternoon/evening” is spam
• Only “Now coffee/a beer/tea” is spam
• Repeating the same tweet over and over again is spam
• More than a reasonable number of tweets per day is spam

To what extent every expression on social media is for ego´s sake is a different question…