Okay, so I'm on Twitter and I generally check for updates at least once a day.
I used to have a policy of blocking followers who followed at least 3 times as many tweeters as followed them because they smelt like spammers / marketers (particularly those that magically tweet every x hours, no matter the time of day or night).
Sure enough, now I find myself edging towards my own threshold of ignorability. (Don't worry, I have a higher tolerance for those who make up words, though the same cannot be said for those who misspell real words).
Perhaps I will have to post a few more fascinatingly followable tweets to balance the ratio?