We're not talking about curation trails. Those are arguably still manually curated, because someone is reading the posts before voting, hopefully.

The "bad" auto-voters are the ones that just vote around 5 minutes on posts by a specific set of authors that are expected to generate content that won't get downvoted. It's bad because no one is judging the contents of the article in that case. Right now, variations of this type of bot are probably the most economically rewarding.