I think classist and elitist the first idea.
Whitelist: do not downvote if the user is on itr
The more control, the less freedom, the perfect formula for steemit's failure, with reference to history.
Bidbotted percentage: downvote only if bidbots represent x% of the payout.minimum payout : only downvote if the post has reached x$ of potential payout
Number of words / characters, only downvote if the post has less than x words / characters
The request lacks to vote negatively on account as the positive vote does, it only does it following a trace of another, it takes away people's own criteria.