Bid bots nowadays are not that profitable and most of the articles trending page were using bid bots. Some of our fellow steemians used bots in a losing bid - imagine, the bots only have 20 dollars maximum vote but he bids it with 15 SBD, LOL.
Bid bots give both positive and negative impact on steemit community it is just on how we see it. But somehow, those empty articles appeared on the trending page due to bid bots. But in some way, bots also beneficial to us esp to those minnows who needs more exposure. We just need to have guidelines or standard on where and when the bots to vote or decline every bid. But the problem is how to determine the quality of the post.
You dont determine it yourself. It doesnt matter what the "objective" (if there is such a thing) quality of the post is as long as you let the community decide what they want to see.
Bots take away that chance completely.
There are black lists and white lists but there is a gray area in between as you mentioned