How this can be done - I don't know, but this should be the goal.
Pretty sure allowing authors to chose how much percentage they want to give to curator would solve this.
People like me delegate to bot because its more profitable than curating, as I explained in this post https://steemit.com/steem/@snowflake/enter-a-whale-s-mind. The vote buying popularity came as a result of reducing curation rewards from 50 to 25%. So making curation more profitable would encourage manual curation. I know that if I could earn as much as with a bot by upvoting content that I like I definetely would do this.
RE: Operation Clean Trending