I try to keep my main Twitter account public, so from time to time I go through my followers list to weed out obvious spam, trolls, and accounts that just waste space and waste my time. I'm not interested in acquiring thousands of followers just so I can say I have xx,xxxx followers. Twitter is supposed to be about business and networking, and if those accounts aren't helping with either, then there's no point in them following me.
I've found that if you don't weed out your followers list, you end up with at least 95% of your followers being spam/fake or other useless accounts.
I want quality, not quantity. Capisce?