diberry - 6:03 pm on May 29, 2012 (gmt 0)
There's no such thing IMO. But there's a huge variety of opinion on the subject.
I agree, but the experts at the Google support forum do not. A few years ago, one of my sites suddenly lost visible PR. I posted that I believed Google thought I was selling links (I wasn't), and this was a penalty. All the experts said, nah, you're fine, you just need to build some better inbound links. I told them I had never engaged in trying to create any kind of inbound links - I just wrote pages I hoped people would like enough to share. They kept insisting I should do more, so I asked them precisely what link-building strategies were acceptable to Google, because all I knew about were directory submissions and crap like that. They, um, kind of had somewhere else to be suddenly. ;)
What I took away from that is: Google is they're lying through their teeth about how ranking really works, and they assume most of us know that, but no one is supposed to tell the truth out loud.