Right. GA should have known something was seriously wrong as soon as he smelled the car. Same goes for CA, being a nurse. But I think at the time the last thing that might have immediately crossed their minds would be that was Caylee was dead and had been in the trunk.
Makes you wonder, though, why they didn't think Casey might be dead given she was at that time missing in action, and there was the smell in the car. As for cleaning, I think CA did that after she shuffled GA off to work, telling him she would take care of things.
I honestly do not think they knew anything about what had happened to Caylee at that point, but I cannot figure out why they didn't know because given both their professional experience you would think the smell would be undeniable. I guess it may boil down to us looking at it from a different point of view than parents in the thick of the unfolding situation would. I mean, who among us would immediately jump to the conclusion that our daughter had murdered our granddaughter and piled her decomposing body in the trunk? Even those of us who might have LE or nursing backgrounds might not go there in our minds right away.
I'm not defending their actions, just trying to put myself in their positions in the first minutes after retrieving the car.