Therefore, it appears that Rogers was aware about the presence of a contaminant which would give a mass spectra quite similar (identical?) to the one actually observed for his mass spectra of Raes sample. Despite that, he did not mention these foreign peaks due to the contamination in his discussion of the spectra. There is no need to explain that plastic bags were not widely used around the Middle Age, and that if there are peaks coming from that material in a spectra these can only be due to modern contamination.
Mass spectrometry is widely used today in the identification of pharmaceuticals, drugs, food additives, toxins. Ironically, even the C14 analysis is based on mass spectrometry. What would happen if we started to interpret mass spectra in a completely wrong manner, e.g. in the similar way as in the Rogers paper? Here there are some examples: a drug dealer could not be condemned, food contaminated with high level of pesticides could be sold, an athlete putting his health at risk with doping could not be stopped, a lot of medicine with a toxic impurity could be given to patients.
There is no ‘innocuous pseudoscience”. Any pseudoscience is damaging, since it alters the perception of the real world and it is deeply non-educative. It might cause serious consequences, especially when health issue are involved. To believe in the pseudoscience of the Shroud has nothing to do with Faith, and especially believers should get offended versus people exploiting either their Faith or the human weakness of the chemist Rogers.
You will want to read this and think about it.