Even IF 8.5 would be a low rating, that's the least of the scores you got there. Eps which where "grossly overrated" got a 9.5. That's not "pollyannish", that's just making sure the show gets a high mark.
So here we are. The trolls you where talking about do not exist (I ploughed through most of the show's scores for this), and all the low scores it got have been substantiated with reason. There are however people who're doing just the opposite.
The trolls argument is not valid, and is even the other way around.
So no, the ratings aren't low because of "trolls who come here just to give the show a low score". The show is sub par, and people rate it that way. THAT'S the reason, no matter what excuse yer trying to find.
The trolls we were talking about do exist, even in this reality. As I said, one persons pollyannish ratings don't make a shows rating higher than you want it to be.