My suggestion is to limit the use of voting bots. Users who have bad reputation and users with high SP power above 5000 SP should not use voting bots. That way only Minnows can benefit from the voting bots, because Dolphins and Whales will end up anyway on the trending page.
Voting bots are made to support Minnows and make their posts visible.

Another suggestion is to push all the promoted posts whether by Steemit or voting bots to the "Promoted" section. That way the "Trending" section will stay clean all the time :)