Under what circumstances does the community user upvote answers?
As a side note, why does it not have the civic duty badge?
Community user holds votes of all deleted posts, deleted users, votes on posts which have been migrated but the owner of the post doesn't have an account.
It also holds the votes on Community wiki posts. As for the badges - no definite answer here but I assume negative user ids aren't considered while the badge calculation runs (note that the Community user id is -1)