Favre was actually hated, not disagreed with. I have never known an opposing player that MN sports fans have ever hated more. Then he became a Viking and people raced out to buy his jersey and crow at their Packer fan friends with every win. People dropped that hate in a second because sports has a "my guy" aspect that is hard to resist. If a player makes your team better you like him.
I hated Favre a bit less, and I was certainly happy to accommodate his vendetta against his former team. (No, not the Jets.) I know plenty of #4 jerseys sold, but I certainly never owned one. One thing about Favre is the hate as 100% football hate, not personal.