Another researcher has also questioned the concept that the amount of carbon 14 in the atmosphere is a constant. That individual felt that the amount present is impacted by volcanic eruptions which increase the Carbon 14 content in the atmosphere, and by extension - samples.
It also seems improbable that the Shroud, being confined in a container which was burned in a fire did not receive a fresh infusion of carbon 14 contaminant at the time of that incident.
I have also read about the errors in the sampling methods and agree with you there.
Palynological studies on the pollen indicate the Shroud spent time in area of Jerusalem. Sample of pollen taken from the Shroud area around the head of the image came from an eastern Mediterranean plant which produce wicked thorns - the type of thing the mock crown Christ had on his head may have been made from.
When you combine all this with the anatomical evidence, the inability to explain the method in which the image was made, the peculiar nature of the image, and evidence from the weave of the original Shroud material, the evidence is very compelling that this MIGHT have been the burial Shroud of Christ.
Re: the bioplastic theory
The bioplastic theory in which hundreds of years of bacteria live, excrete, and die on the fibers of the Shroud, adding enough newer C14 to that already present to skew the test results by 1300 years fails on several grounds. First, the type of bacteria that lives on linen eats the linen, absorbing the C14 of the linen and therefor would have a C14 date approximately the same as it’s food, the Shroud. Secondly, to actually skew the date, assuming that the bacteria actually does injest contemporary Carbon, then some of that “bioplastic” would be just as old as the base material of the Shroud, and some would be progressively younger until you get to some that died yesterday. The amount of this “bioplastic” would have to weigh as much or more than the original weight of the Shroud to skew the date by 1300 years. Finally, it just is not there. The fibers of the Shroud have been examined microscopically, including optical, spectrographically, and scanning electron microscopy, and both the “bioplastic” and any Carbon soot pollution are just not found. Once it was understood that what was tested was a mixture of about 60% to 40% newer citton added to original linen flax, all of these pollution theories became moot. We know what skewed the date. We need look no further.