Twitter influence ratio (2009)

I received a Tweet the other day and it was from someone I did not know in a field I was not interested in. The post said something to the affect of 'I have followed you, now follow me and then unfollow in order to complete the opt-out process'. When I started my Twitter account, I went to some of the communication and PR twitter accounts that were of interest to me and then followed some of their followers. The thought was...