Good point SS!
But I have to think weird sometimes when it comes to this case.
Not Cindy or George, but Casey using the cooler to get the toys into the back yard in one trip.
In my weird thinking, Casey looked around the garage real quick, spotted something that could drag the toys all in one trip to the back yard and thought nothing of just putting it back on her way back to the car in the driveway.
If the toys were in the back seat and the toys were plastic, they might not have absorbed as much decomp smell.
The lid of the cooler was on. The little bit of decomp smell that could have come in contact with the cooler was contained inside the cooler.
George nor Cindy had any use for that small of a cooler for 6 months. Nobody bothered with it.
The lid was on, keeping any scent inside it.
LE/FBI looking around during the search just after finding the remains, had to think diabolical, like Casey.
They took the cooler just in case 'there might be something inside to test'.
Like I said, this case has me thinking really, really weird thoughts and ideas.