I think the ref's have an unconscious bias for and against teams and players. The bias is fed by media commentary, past experiences, location of the event, impact of the outcome (how result plays into a fairytale), influences from other refs have(through training and how another ref conducts themselves on field) , and perhaps even social issues. They pick up on the general "vibe" a club or player has within the broader community and make judgement on that. We all have unconscious bias, and it takes alot of effort, and integrity to stamp it out.