Amos -

My impression is that Google, and most other search engines, do include commercial/sponsored chat groups. If someone in one of those posted a link to the 'cat in a discussion, they'd find and incorporate it. It's the other world appearance of something on the 'cat that gets posted.

I occasionally use Google image search to look for art work, and very rarely find a link to one of the numerous .org sites, but only if one of the "poster sellers" has linked it on their commercial site.

If it's printed in the "news" by a magazine, newspaper, or tv channel/program site, it gets listed.

NONE of the available search engines I've found will consistently tell you if some university network has that ancient text on "blowby leakage in manufactured hydraulic seals" ... so important to the serious researcher...

It's easy to forget that only the "pop culture" is indexed. And tough to decide which is the real world.

John