In the 7 months that I've been here I did a follower purge and started from scratch twice. The first time was because I was new and had big shiny dollar signs in my eyes from all the lucrative posts. I thought if I followed them I might get some of their ju-ju even if they were blogging about things I didn't care about.
The second time was because I wanted to have a fresh feed and rediscover people. I suppose I should go through deadfollowers to see how many people are inactive but honestly, if they're not active they're not messing with my feed anyway. LOL