Unlinked domains with Matching Whois Leave Clues to Webmasters Intent

[Halfdeck]

An observation about how Google might use whois information against you even if your domains are unlinked and are on multiple IPs/hosting:

"Back in November the big news from Pubcon was that Google imparts intent when evaluating a web site for "quality". Matt Cutts had accepted an invitation to participate in an open review of web sites, and had done a whois lookup on a publisher as part of that process. While examining the web site presented for review, Matt commented on "other domains" that publisher held, as if it were somehow germaine to the discussion of the particular domain under examination. The webmaster stated his "other domains" were unrelated, and not even linked to the domain under review. Matt acted as if that was irrelevant. Several SEOs in the audience were offended. What did other unconnected domains have to do with the one, published domain under review?

Matt didn't clarify, but it was obvious to me and others that Matt was seeking to impart intent upon the publisher. The other domains were considered clues, additional information about the character of the web publisher.

Matt was directly questioned by the audience on this issue. He said yes, the existence of additional domains with matching registration information is directly relevant.

(emphasis mostly mine)

So, according to this view, if you own 3 legit domains and 1 black hat domain all with an unprotected whois, that black hat domain can negatively impact the ranking of your other domains even if none of your domains link to each other. Or if you own 5 adult domains and 2 mainstream domains, your mainstream domains can rank lower if Google finds spammy linking patterns on your 5 adult domains.

http://www.johnon.com/312/google-algorithm.html