well you have to think that most adventures are evil, your making money by killing people, taking there stuff, and sometimes getting a bounty on there heads. Lets think how people would react if a small group of people went to LA and killed all the Bloods, took there stuff and tried to resell it. I think most people would take that as a evil act. Now lets think of this you walk into a bar the barkeeper is a lv 5, he was a adventure before he opened up the inn, now he is evil not because he kills people but he steals form them and he treats his employees very bad. Now a pally walks in a detect evil the barkeep is evil so he sees that he is evil, now pally walks up and stabs the barkeep through, I dont think the town guards would be that happy with the pally, and the defense of I killed him because he was evil would not get him off murder charges.
Anti magic field half the way up, bag guy fly's up and triggers an anti magic field trap, players fly into it, now they are not flying :p and now they are falling in a anti magic field. or you could have them run into a anti magic field that takes up a large area, so they have to use common ways to follow the bad guy.
yea one thing my party starts to do around lv 3-5 they only will pick up master work items or magical items, they dont want to write down every thing to sell it, and when it comes to the gear that would be worthless like a dog slicer or a troglodytes armor I tell them that they cant sell it and I just put some extra gold around for them to find.