The easy commenting facility that is available on blogs and social networks are enabled by commenting engines like Disqus, Facebook Comments or Intense Debate. It makes interaction easy and quick but leaves a glitch in the process: the comments cannot be searched by any search engine since they are written in Javascript. In other words, your comments on any sites are simply not found by SEO because of coding issues.
But now Google is taking care of this problem by programming their Googlebots- digital spiders to crawl onto web pages and fetch them- to get comments from sites as normal text. In fact, you can even find a comment by typing it in the search box and Google will fetch you the proper details of it as it does for any usual text search. Matt Cutts said, “Googlebot keeps getting smarter. Now has the ability to execute AJAX/JavaScript to index some dynamic comments.”
Here’s an example of how a comment by Robert Scoble on TechCrunh was viewed earlier:
This comment was found by Google in the following manner:
Not just this, you can even put in all the details of the persons whose comments you wish to see, for example, “commenter name * commenter title” ( “Robert Scoble * Chief Learning Officer at Rackspace”) and all comments given by that person on all sites will be made available.
Google, however, is unlikely to pass the information about who is checking your comments to the commenter. Now, the comment text is a part of the page content itself so if you have made any profane or ugly comments any where then you may fall in to some trouble as per the Google’s Webmaster Guidelines.