patc - 3:53 pm on May 3, 2011 (gmt 0)
+1 for ponyboy. The whole argument falls apart unless you believe that it fits into the words "Almost nothing" which Google assert is how much damage your competitors can do for your ranking.
I'm not discounting the idea, I'm convinced my site tanked because of this (wasn't Panda though, was 12th Jan - a pre-panda clearout?).