One could say our fans are thugs.
I went to the Juve v Verona game this season and was shocked by their fans. They were spitting on and throwing sticks at kids/families in a section of the stadium that is completely harmless and had no interest in any wind-up between the fans.
I have been to a few Juve games, usually sitting near the opposition fans section and they were by far the worst.
I have no issue with opposition fans winding each other up and even the odd bit of violence. What I do not like is people attacking others who have no interest in that sort of thing and just want to enjoy the match.