This is documented in our quality policy.
We automatically capture blacklist status from Buildawhale and Steemcleaners blacklists. If somebody is blacklisted by those services, we encourage them to follow the appeal process for the service they were actually blacklisted by first, since being on that list will cause more issues than a mere cessation of SBI votes. If they successfully appeal, then it automatically resolves their SBI blacklist status as well.
If they are unable to appeal to those services directly, then we perform our own review of their account. In review cases, we focus primarily on their recent activity, but give some suggestions for how they can improve their overall standing in the community. If we agree that their recent activity is not abusive, then the reasons they were originally blacklisted are less important to us.
In the event that I (@josephsavage) decide not to override their blacklist status, and they dispute my judgment, there is a more formal appeal process.
For the record, while I have often seen accusations brought against Steemcleaners, I have yet to see actual evidence that convinces me that they are a 'shady' service. They typically downvote multiple times before applying a blacklist status, and accounts that I have suggested to appeal have been successful in having the blacklist status removed.