I went to the Philly game the last time the Colts played there. That was the game that Austin Collie got carted out on a stretcher. The things that were getting shouted at him while he was lying on the ground waiting for the stretcher were......well......I don't like to think about them. At pretty much any other stadium that I have been to, the fans will back off some and show some respect to a seriously injured player.......especially while he is lying on the ground immobilized waiting to be carted off the field. Not Philly. They literally add insult to injury.
I've been to Colts games in Baltimore, Washington, Philly, New York (well, New Jersey really), and New England. (One of the benefits of living in the northeast. Lots of NFL stadiums within day-trip range.) Philly, in my experience, is a different animal. You get taunted any time you go to an away game. That is a given and expected. At every other stadium that I have been to, the taunting was just good natured ribbing. Philly was the only stadium where I felt like I needed to watch my back. Now, nothing ever got out of hand, but it definitely felt less like good natured ribbing and more like a message. "You are not welcome here, so occupy the seat that you paid for, shut up, and keep to yourself." With that said, I will probably go again this year if I haven't moved out of state before then. It wasn't bad enough to keep me away.
My general rule of thumb at away games is, "Do not escalate the situation." For the most part, people will be cool but you are bound to have a few *s that try to start something with you. When that happens, just let it roll off you and don't escalate it. They generally don't persist if you don't give them the rise that they're looking for. It's not a home game, so don't act like you're at home.