Anyone looked at the ratio of internal to external links. I'm tracking the top 200 health websites and see that 84.2% of Panda II losers have very high (uneven) ratios (e.g. above 65%). All of the winners have much tighter ratios (e.g. sub 40%). This is the only common theme that seems to be universal.
On a positive note, 8 out of 8 of the top 80 health websites hit by Panda have recovered a bit week/week between 4/17 and 4/24. This includes those with uneven ratios. That is, all but one which is clearly a farm. None have recovered anywhere close to pre Panda II levels.