eZeB - 3:32 pm on Feb 22, 2005 (gmt 0)

I think it is quite a bit more complicated than simply blocking PR transfer from high PR sites.

After all, they have 8 Billion sites to play with, so that is a pretty huge statistical base to run tests on. They get a few thousand known examples and chew at them and could easily come up with a list of 20 characteristics of paid links.