Here's one of several references that could be posted regarding Google's expressed intention to bring iframe and user experience in line with each other. Note Matt Cutts' commenta....
Iframe Links: Do They Pass Page Rank? March, 2011 http://www.webmasterworld.com/google/4282550.htm [webmasterworld.com]
Eric Enge: If someone did choose to do that (JavaScript encoded links or use an iFrame), would that be viewed as a spammy activity or just potentially a waste of their time?
Matt Cutts: ...In my experience, we typically want our bots to be seen on the same pages and basically traveling in the same direction as search engine users. I could imagine down the road if iFrames or weird JavaScript got to be so pervasive that it would affect the search quality experience, we might make changes on how PageRank would flow through those types of links.
It's not that we think of them as spammy necessarily, so much as we want the links and the pages that search engines find to be in the same neighborhood and of the same quality as the links and pages that users will find when they visit the site.
The current discussion is regarding content, not links, but I think the underlying issues are the same. Clearly TheMadScientist is aware of these issues as well... thus his emphasis on "might" etc etc. Use of iframes is a technique where we've been assuming its days would be numbered. Ditto with javascript writes.
While I'm guessing that Google might eventually also use OCR to read text content in graphics, I have successfully used graphics, as aristotle suggests, for some boilerplate or headlines... occasionally for a paragraph... but never tried it for extensive comments. Seems to me that would be pushing things.
I've seen comments referenced simply by posting an excerpt only on the product page and then linking to a separate comments page as TMS suggests for the full set of comments. The question I would ask is whether all the ajax subterfuge gains you anything, or whether it might demonstrate deceptive intent and ends up hurting. It might be cleaner simply to link to a noindexed page and then identify these comments as "comments from elsewhere on the web" or some such.
I haven't tried this, but Google in its recent enhanced shopping results has shown some kind of acceptance for shared reviews of a product....
Searching a product shows reviews, what others are saying, specs, etc https://www.webmasterworld.com/google/4756131.htm [webmasterworld.com]
Admittedly, Google is not constrained by dupe content requirements of organic search in these paid ads, so we need to be cautious in assuming it's OK... but there is an aspect of collective opinion about a product that seems to be acknowledged here by Google. I think that the acknowledgement of "what others are saying" would be an important part of this... along of course with the permission. I'm assuming the noindex would be necessary.
