Being a PHL
resident and spotter, I can safely say that photography at PHL
is a coin toss. Sometimes the police could care less about spotters, sometimes they do. If they have a problem, they'll usually tell you to leave, without any hassles (unless of course you argue with them as my father an I found out in March). If you're going to be in a car, I'd say stay in your car until aircraft arrive, then hop out for the photo, and get back in again.
If you'll only be spotting from inside the airport, I can't help you with that. I don't think they have any problems with photography from the terminals, but I haven't been in there since pre-9/11.
I think Big Foot is blurry, Its not the photographers fault. Theres a large out of focus monster roaming the countryside