Maybe I'm part of the minority here, but I just didn't see the look/smirk/whatever as Casey rewarding CA. It seemed more resigned to me. Like "Thanks for throwing me under the bus, mom, but I know you were trying to help." and CA saying "I know I threw you under the bus, KC, but I was trying to help."
I think Casey is a narcissist and self-entitled and probably a sociopath, but I do think she's probably a realist. This works to her advantage and against her. She acknowledges that this case is going badly for her and might very well have adopted a "Blue M&M, green M&M, it's all the same color in the end" attitude. Does she believe she'll be convicted? Maybe, maybe not. Do I think she really cares? I don't know. Maybe not right now. I think being a cause celebre might be an interesting thing for her. She probably feels like she's walking a catwalk whenever she walks through the holding room door. I think she'll lose that feeling fast once she's convicted and she's no longer getting her lawyer visits and the frequent excursions to court.
I think KC is heinous, but not an idiot. She has to realize this is going abysmally for her counsel, and for her. Maybe she lives on the hope provided by her circle, but there has to be doubt there.
I think she's being civil to CA not because she's kind, but because she knows it ultimately doesn't matter. Kill them with her brand of kindness so they live a life of guilt after the trial is over and she's convicted. She's won. She took their beloved Caylee from them and it's now ALL about her. Mission accomplished. The fact that she doesn't have freedom right now is inconsequential. It may become real later, but now she probably feels pretty good about herself. "Sure, mom. I love you. You're an awesome marionette."