Maybe @steemcleaners can publish a bot abusers digest that bots can ... digest as a blacklist. This way bids from certain blacklistees will just be auto rejected.
@steemcleaners digest can be crowdsourced by users.
I recommend this because some people are not in the habit of useless posts. They also aren't trying to abuse or they think information is generally useful that others do not. Some of these are newer users that just don't know any better.
I think having a curated blacklist that users can get on through community vetting and also maybe earn their way off by producing valuable content would be useful. Not only would some users not be offended, but there's a path to rehabilitation for abusers.
I'd like to point out that @steemcleaners has created an economy out of crowdsourcing abuse vetting curators. I think leveraging the data they mine into bot abuse is the obvious move.