A few times I've found the account is over a year old, but comments only started recently. If the front page of their comments was filled (i.e. 10 comments), I probably wouldn't have noticed this. BTW they didn't seem especially bad, just the typical newbie comments before someone replied "Please elaborate".
>>10ren+(OP)
It might be worth doing one more version considering the ratings only from people who have contributed significantly to the culture (their karma along with age should reflect reasonably well i guess)