For what ever reason, CA knew she had to clean that pontiac pronto, and I think she knew how difficult cleaning the car seat would be. I'll bet they owned more than 2 car seats, probably 2 Eddie Bauer black & gray. CA most likely bought 2 Eddie B at the same time and possibly SA has proof. Can't see casey wasting her stolen $$ on a car seat for caylee. Maybe SA looked into "recall notices" sent in by CA, I know I'm faithful about sending these in.
Between my home and SUV, I have 6 car seats for my grandkids, cuz I don't share with DIL's, too difficult to move from car to car and they keep em' as clean as I do! Sippy cups leak, french fries, cookies, etc get wedged in those tiny..tiny little spots. We all have "extra" car seats, and I store the used ones that I've replaced. Yeap, I am the car seat cleaner for all in my family.
I think CA would not want the car seat to look and smell like it was just cleaned. IMO, she had GA toss it out on his way to work that day, cuz she knew she had another one just like it.