Commented out text and Google

Is the commented out text unique for each page or the same on every page? Is this text a small percentage of the page or a large part of the total page weight?

Unique on each page that has it. Small percentage. Usually refers to product specification changes so that we can track them.

I've never seen Google pay any attention to HTML comments. In fact, I've seen strong evidence that they are completely ignored. It only makes sense. People stick all kinds of things in comments for a wide variety of purposes. I can't imagine why a search engine would do anything else. And as far as Panda is concerned, Panda is aimed at the user's experience and since HTML comments are invisible to users, there's no reason they should have any effect.

In the olde days, when some people believed that text in comments might have an effect, I ran several tests looking for commented-out unique text strings, just to clear up any argument... and I've never found any evidence that Google indexes such text. Never.

There is a way, though, I can imagine that text in comments might perhaps cause difficulty, even though Google doesn't index such text....

In public site reviews over the years, I've seen Matt Cutts make wisecracks about spammy comment tags he came across, and I can imagine that if you had a page filled with a bunch of such comments... I mean really stuffed... and the Google spam team did a manual check of your site and found it otherwise questionable, the stuffed comment tags might suggest to a human reviewer that your intentions were manipulative. Google is big on intent, and it's conceivable that spammy but ineffective comment tags might tip the balance of a close opinion against you. Unlikely to happen, but conceivable.

Usually refers to product specification changes so that we can track them.

No reason whatsoever you should be concerned about these.

Usually refers to product specification changes so that we can track them.

No reason whatsoever you should be concerned about these.

these would only concern me if i preferred not to expose the contents of comments to visitors.

these would only concern me if i preferred not to expose the contents of comments to visitors.

Along the same lines... having to do with concerns about exposing comments to humans (as opposed to Google's indexing)... I've occasionally had clients who (prior to my involvement) have made references to seo strategy in their comment tags, as in: "page for seo", "heading for seo", "text for seo", "links for seo", etc.

Apart from the fact that I don't think that seo strategy can be grafted onto a site this way, this kind of exposure, IMO, is not a good idea. ;)