I have noticed users have been going through other users posting history purely just to down vote every post that user has made out of spite for one thing a user has posted.
DO NOT DO THIS
You are hurting the site as a result of doing this. While a user may post something stupid, only target the specific post. A user may have had useful posts. Down voting signifies that the post is unhelpful and should be ignored by other users. If a new user who knows nothing of some isolated incident reads posts down voted in this manner, they may be puzzled and incorrectly ignore helpful advice because of this.