Here's a little thing I noticed a few days ago...
I had a site where quite a few pages were (quite well written) PLR articles repeated so often on the internet that my pages weren't even showing when you searched for a sentence from the page. So I removed the pages, thinking it was a waste of time having them, and planning to rewrite them in due course.
Doing keyword research for the same site a couple of days later I found a good keyphrase and was looking to see the pages that ranked for the phrase. Surprise! One of the pages that rated highly was one of the 'non-existent' pages I had just removed from the site - because the phrase exactly matched the 'title' I had given the page.
So it was showing for a moderately competitive phrase, but not for a completely uncompetitive whole sentence from the page.
Who cares? This tells me that even a free/PLR article can be useful to a site, and show in the SERPS, simply by having a well chosen title, even if the content of the page is 100% duplicate.