I've been to several Raiders-Bills games in Oakland, and I've worn my full gear every time. Never had a problem.
Every time I went, the Bills have always lost. Leaving the Coliseum and hearing the fans yelling "RAAAIIIIDERRRRRRRS!!!" every time you pass one gets very nerve wracking.
I was at the Raiders-Chiefs game last week, and wearing my Bills jacket with a big Bills logo on the back. When the game was over, I got noticed a few times.
One couple was asking me why I was there, because I was a week early. I laughed and joked backed with them, it was all good.
Then later another couple walks by me, and this young lady was yelling F%@* BUFFALO! I told her if it wasn't for us, you wouldn't exist anymore. Obviously she didn't know what I was talking about. Then she admitted that she has Buffalo's defense on her fantasy league, then she said "F Buffalo!" again. Whatever.
I admit this week's game is a grudge match to me. I really want the Bills to win.