I'm having a hard time believing that these girls are as truly as bad as they are behaving. A common theme through each episode has been, watch them screw up intentionally, hide the evidence as if no one will notice, and see if they can get away with it. This is so juvenile, the producers have got to be putting them up to it. I went to high school with a lot of famous people's kids and obscenely rich kids (one of the same schools Paris went through, in later years.) None of them ever behaved with such a complete disregard for others.
I buy that they are naive and silly, but there has got to be somebody behind the camera, whispering, "flip off the passing cars, that will be really funny." And so they do. When we were filming Monster House, they asked us go to the beach with a cameraman. We arranged it for a Wednesdy afternoon after school, and Chris came home early from work especially for it. The producer told my him, before we left, to make sure to say something like, "We hope you aren't working too hard back at the house, while we're at the beach!" I told him not to say it, but he doesn't watch reality TV, so he didn't know that was a trap. He said it just how they wanted it, and they juxtaposed it nicely with a shot of the workers slaving under a deadline crisis (and our woman welder crying under the stress of it). Over on the Monster House boards, people hated us! They actually ranted about how terrible we were.
I honestly believe that Nicole and Paris were goofing around for the camera, with the knowledge that this isn't real (the auction guy isn't really going to get stuck with the bill, we all know that and so do the girls.) They just didn't get that it would all appear on TV as if it was real, and how horrible it was going to make them look.