I’ve just come across this freebie web tool that gives you a quick and dirty method of checking if your site is under a duplicate content ‘penalty’ i.e. is your content being pushed into the supplemental results because the pages are too similar.
Oh, and don’t forget you can always use copyscape.com to check your sites content against your competitors which is a great way of ensuring your saying something unique and discovering who’s poaching your sites content.
I was actually hoping it would do what they state here: “(4) It checks for supplemental pages in the Google index.” and was also scratching my head about how exactly can they do that without starting 100s of automated G searches (and getting banned by G for that).
I tried one domain and the problem is solved! item #4 was actually a wishful thinking on their part and mine. It does not actually preform any supplemental checks. Shame, really, since all the rest of the tests can be easily done by hand and supplementals were a great candidate for automation.
if you spot them actually implement #4, post a comment here please, I should get an email notification and try again.
Cheers!
S.