Some think this is not a problem because if you write a unique article you can post it to ezine, articlesbase, and other popular article directories without changes (at least most allow this according to their terms of service). Basically if you are going to republish without spinning your content, the site that gets indexed first gets credit for original content. I personally spin my content. However if I will be lazy and republish without change, then I will put the content on my site first and wait until it gets indexed before posting it at article directories. Big G finds dupe-content all the time and puts it in their supplemental index. While you create a backlink, I believe it does not have the same value as a backlink that is found on a page with unique content, thus the reason I spin my articles (whether this is black hat is purely subjective and up to you to decide), at that is my 2 cents.