SEO Tip #107: Can I Specify The Canonical Of All Of A Product’s Review Pages As A Single URL?
Yay or Nay: putting a canonical tag on individual product review pages that each points to the ‘all reviews for this product’ page for the particular product. Assuming we’re not really that keen on the individual review pages ranking.
Matt Cutts: If I understand what you are saying, imagine that you have a product page for a red widget or something like that and you’re saying you have individual pages for small little snippets of reviews. Rather than having those four or five small little snippet pages, one page for a short review and another page for another short review, rather than having each of those individual pages ranking you want to put a canonical tag on each of those pages to point to the overall product review page. That is a perfectly reasonable way to use the ‘rel’ canonical tag.
Now you probably shouldn’t do something that is vastly, vastly different like canonical from a red widget to women’s shoes or something like that that’s completely unrelated. But something like individual product review pages or individual URL’s to a sort of global or master page for that particular product is a perfectly reasonable way to use ‘rel’ canonical tag.
Now be thinking about it in that those individual pages might turn out to convert well so you want to do some testing. You don’t want to just blindly say, “I think this is the best way to do it so I’m going to just plunge straight ahead.” Look into the conversion rate and all that sort of stuff. But if you reasonably conclude that you would rather have those pages all glommed into one that is something you can do with ‘rel’ canonical.