How are people getting private ids ?

I was just wondering how people are getting these console id's " Private " .
Are they Generating them ? Getting them from ps3's that has been Jailbroken , Or maybe some who did back ups for people in the past when it wasnt patched , Kept their console id's .

And whats the percent of people selling console ids that are REALLY private , can't they just sell a private 1 to many people ?