Just reading around a lot, researching heavily, read a few times of affiliate publishers using private whois on their domains promoted through PPC. Just wondering if this is the norm? or just a personal choice. Any particular reason or do you simply not do that?
They don't want people contacting them or they are running multiple sites and don't want to share that with google. Some people crosslink their sites from different class c ip addresses and they are more likely to get away with it if the whois isn't public since google is a registrar and can link common ownership through whois information (this isn't likely to work if you go from public to private vs. initial domain registering with private whois in place.)