IMO, the smell in the car was some of the most telling evidence the SA had in this case. Most of the evidence was strong, IMO, but the evidence of decomp in the car proved that a body had been in the vehicle during some level of decomposition.
IIRC, one of the jurors (may have been an alternate) said after the verdict that they were not convinced Caylee's body had been in the car. Considering how much the decomp smell was talked about at trial and the level of expert testimony presented about the smell, I find it highly questionable that the jury was not allowed to witness that smell. I would bet that even those who had never smelled decomp before would have been convinced that the smell in the car was not trash (or garbage).
Why the smell cans were allowed to be introduced as evidence but not allowed to be opened, I will never understand. If evidence in any form is not allowed to be witnessed by a jury, the defense then has a huge advantage. If seems to me that if physical evidence can be "witnessed" by jurors with their eyes, smell evidence must be allowed to be "witnessed" by jurors with their noses.
People who had smelled that car have said they had no doubt about the smell. It is just unbelievable that those who needed to be convinced about the evidence in the case (the jurors) were not allowed the opportunity to examine the smell evidence.
There is no issue, legal or moral, IMO, with the car being destroyed. The perp has been set free and can never be tried again for this crime so no evidence in the case needs to be preserved anymore. I do not believe George's intent was to destroy evidence; IMO he chose the best way possible to get rid of a vehicle that was of no practical use to anyone.