This is not based on any kind of scientific proof, so take it for what its worth, which is simply an opinion. But we can discuss and maybe its not true and I'm harping on a few examples.
But lately I get the feeling a lot of people are getting sick of the Packers fans whining and crying about Favre considering the success he gave the Packers, especially from fans of lets say "not so good" teams. For example, like the message boards or comments on articles on ESPN or whereever, a lot of people are throwing out comments about how Packers fans have no class for crapping on Favre for wanting to play, etc.
I have a lot of friends that are fans of the Lions because I'm from Canada and they can't stand Packers fan anymore. I said last year that they shouldn't crap on Calvin Johnson so much because he's solid, and they have not let me live it down because they keep comparing it to the way a lot of Packers fan talk about Favre - "we're 0-16, you had ONE losing season in the past 16 years".
Like that whole burning Favre gear, crossing out #4's and replacing them with #12s on jerseys, the "Brent Who" shirts, etc. Do you think it has created a kind of Packers fans "spoiled" resentment from fans of crappier teams? I was in the mall the other day and some guy had a "In with the New, Out with the Old" T-shirt with a #12. Like I ordered a Rodgers jersey from a friend because he's our QB (do I still think Favre gave us a better chance of winning last year, of course) but he is our QB and he's done very well. But I don't know why you have to crap on Favre at the same time.
I get the raw emotion from having a fan favourite going to a rival fan but not all NFL fans see the story the way Ted Thompson and Mike McCarthy make it out to be. And some fans I think conclude that he wants to play and the Packers didn't want him so he played somewhere else - why destroy 16 years of memories - life goes on.
When the media was loving Favre, the average fan hated him because he was stuffed down their throat. Now the media has turned on him, I think the average fan is hoping he proves them wrong.
My friends are now the biggest Favre fans, just so he sticks it to the Packers and their fans (me included). Their thinking is that they hate his off-field drama, etc. but on the field, they always respected him for heroics and playing hard and they don't get the crapping on Favre stuff.