I wonder as well, because hair , fibers, would be found wherever the child was and so therefore..wouldn't mean much. The transfer of fibers or hair belonging to any of the Anthony's would mean nothing because she lived in that house.
Fingerprints they have already from the family.
I think it is routine to check for anything that ties to body, but I still maintain that everything in the Anthony house would be with the body if this is in fact Caylee. Fibers from her clothes, dna etc would all transfer to the bag as well.
If the bag comes from the Anthonys' home, that is a different story. I have no idea what they hope to find in the dirt from the vacuum. I think they want to tanks from house to see it was used for some other purpose. Perhaps they want to be able to tie the pesticide to the trunk of the car? Did they find that in there? Or was the chloroform in those tanks? Any fibers from the trunk that were transferred to Caylee would be the most important I would think. However, they haven't even mentioned that search.
I guess that is my best effort for the day.