Hey, I mainly downvote posts that are getting blind votes by haejin+rancho on trending posts who may have gotten there blindly by the trafalgar/steempty votes. This is usually limited to either people who get their blind votes too often (blind meaning the content don't matter they just vote whatever is trending at the time), or if it's generally low effort low quality content, which it kind of often is as the votes that get them to trending are auto or just super random such as traf's (even talked with him about it he said just downvote if they land on bad posts :shrug:)
Aside from that we're downvoting some self-voting scheme by the project hope community but that seems to be decreasing now after a few weeks. (they ask their community to set 50% beneficiary to themselves on their posts in order to receive votes most of the time). Other than that I don't believe ocdb is downvoting anything outside of that scope. What posts in particular made you ask? (late reply as I don't usually check ocdb's mentions as they get spammed).