The thing is that you have to realize that the content will be "scarped" (and that is just a good word for stealing) from other websites / blogs etc. so you are getting an illegal copy of content tat is not only illegal but also bad for
SEO and can get you some enemies...
want to find where the text was lifted from - use Copyscape - they use Google API so if they find where the text was copied from you can be sure that Google already knows where the original is.