The prime reason of web pollution is re-blogging. Many die-hard bloggers consider it a sin, a grave sin. Blogosphere or Blogoplanet has been severely destroyed by the re-blogging. Re-bloggers are people (so I’ve read and understood) that simply find others’ content on the internet and post the same stuff verbatim on their blog, with at most a link back to the author on the very bottom.
The most killer pest for your blog traffic is to just write what others are writing about. If you do feel convinced enough to write such a post, do it in your own unique way, try hard to give at least some thing usefully unique to reader, otherwise your blog is doomed to fail and you will be the lone reader of your beloved blog. And I am quite sure, that in future, a search engine would be intelligent enough to understand the content on web and would be able to differentiate an original from the duplicate one.
Another form of re-blogging is to repeat the news of any kind in your posts. If someone has to read the news, he or she could always to go to any news site, they are plenty. Yes, if you want to give your own unique perspective on that news implication, then its all-right. In your post, just pointing towards the news story and towards the links which comment on that news is un-ethical and useless.
So is to write about places, persons and things. If you are just regurgitating what’s already their or its a common knowledge with out adding any unique and subtle points, then you are doing nothing constructive. You are not only wasting your own time and resources but also repelling whatever reader base you have. If you carry on doing this, people on web will make you outcast and avoid you like plague.