Every team has a few of those, even the Giants... but in my experience Packers fans are for the most part a pretty classy group. Trash talking from them is usually good natured, and you will see many come back to say "good game", something you won't ever hear from other teams.
+1. I think Packer fans are amongst the classiest. It's the 49er fans that are now on my s*&% list.