One of the issues in the OJ trial was how the evidence was handled (chain of custody issues, processing errors, preserving errors, etc) and evidence that contradicted itself. Here you have physical evidence on one side that the defense really hasn't been able to touch, vs emotional and obvious desperate family saying otherwise but providing nothing other words.
So we recap the facts:
Caylee was not reported missing by her mother, but by her grandmother, as heard on the 911 call.
Caylee's body, with duct tape, was found buried in the woods in a bag.
Casey likely couldn't tell the truth to save her own life - and here that might be exactly the case.
During the time that Caylee was missing, Casey was happily living life in the fast lane. She had removed herself from immediate family that would have noticed quickly that Caylee was missing.
Suppositions:
In most cases where a child dies accidentally at the hands of family and the body is hidden, there is evidence of remorse. A proper (though hidden) burial, often with a shroud of some type. Generally the face, if covered, is covered with cloth (like the shroud), not duct tape. A story would have been come up with to explain the child's disappearance, like a distant relative or (if she hadn't already claimed he was dead) that Caylee's father had taken her.
Cindy's testimony flies in the face of her 911 call. If you were trying to help someone cover up an accidental death, and you'd had a month to think about it, I'm sure you'd come up with a better story and not sound as panicked (or sound too panicked).
Now, while cause can't be established, manner of death was ruled as homicide. To me, not one of the defense's expert witnesses (I'll use that term loosely right now) has been able to controvert that effectively enough to have manner changed to accidental. They've run around in circles trying to confuse things without actually saying much of anything. It's like watching a political debate, a whole lot of wind with minimal substance.
Do I trust the cadaver dogs? Yup. I know they're not infallible, but they're pretty good, and I have no reason in this case to suspect they're wrong. Trunk, playhouse, burial site (correct me if I'm wrong, I think those are the places). Body in trunk, moved to in or near the playhouse while she's digging the grave in the woods and cleaning the trunk. By this point decomp has set in and that leaked into the dirt there. Trunk, you're talking escaping gases and liquids that would be in nooks and crannies (has it been established that the trunk liner is the original one or a replacement?) that can't be seen or maybe even gotten to, but the smell is there to the dogs. Maybe the body was on a bag in the trunk (hence nothing on the carpet but enough gas trapped in small spaces for the dogs). I do wonder at what point the body was placed inside a bag.
So anyway, that's kind of an overview of my take. I'll take well established physical evidence over personal testimony, and in this case I certainly have more reason to trust the evidence.