Let's assume for a moment that Caylee did die accidentally. Even if her mom drove around with her body in the trunk for days (some people are like that, when my 14-day-old sister died my grandfather suggested she wasn't worth buying a casket and offered a cardboard box from the back of his store) what would be the point in placing duct tape over the mouth and nose? And that's just for starters, the dumb bimbo theory does not hold water!
Granted, but the defense doesn't need to explain all the evidence. They just need to create a reasonable doubt.