[gibwell]

I agree that Google uses one rule set across the whole internet. I don't think they have anything resembling a list of competitors to downgrade or anything like that.

However the algorithm is based on hundreds of metrics, and is highly discriminating. In addition, Google uses human raters to determine what a good quality result is. This is fed back into tuning the weighting of the metrics.

Therefore, the biases and judgements of these human employees will be reflected in the results.