Whenever I post something on my blog, the post title and URL gets pushed to Facebook and Twitter. The URL is shortened via bit.ly. Almost immediately, I will see a couple of tweets of the post information (not retweets of my sharing) including a shortened link to the post and a piggback link to some other website. This second URL is like a parasite attempting to leverage interest in my post to get links and clicks to the other site.
Due to the sorry behaviour of many Twitter accounts of reciprocal following, these parasite spammers can easily build up modest follower lists.
I really don't like this behaviour.