I think she had been pulling off lies to her mom for so long that she actually believed she was good at it. I only say mom because I think GA gave up on trying to get CA to see thru casey's lies a long tie ago b/c he just couldn't win. I am sure that CA always stuck up for KC and GA was always the bad guy to KC, just b/c he was hip to her crap. on with her plan....she thought she was an excellent and witty liar (oh boy I sure fooled mom with those fake emails from my job!!) but she didn't realize CA only believed her b/c it's easier for CA to live in denial than to deal with the truth.( I know soooo many people like this, it's a complete lack of a coping mechanism)
So casey thinks she is an expert liar. I think whatever happened was 1/2 accident, 1/2 premeditated. I think deep down she wanted to be rid of her. I think Caylee was hurt very badly by her mom, and could have been saved, but casey knew she would be in big trouble for causing such harm to her. I think casey let her die and made no attempt to save her. Her plan after that was to just wait til the heat was on. She didn't seem to think there was much urgency in coming up with a solid plan after all she could snowball her mom for years! I think she put caylee in the dumpster at sawgrass, wrote down some random license plate #s to look up later and decide on a name, just in case she was discovered. Ultimately, I think she planned to move out to Cali, keep telling her parents caylee was with her, tell the guy in Cali that Caylee was his and that she let someone adopt her. Basically keep up the charade 3000 miles away. She in no way ever dreamed that amy would bring her mom to tony's. man I would love to see a polaroid of her face when CA walked in.