Some couldn’t know, say, if they’re anosmic. My wine connoisseur niece used a homeopathic zinc-based nasal remedy and became anosmic (fortunately, not permanently, but the recovery took a long time and wasn’t 100%). She could have munched on a potato or apple blindfolded and not known the difference, because she had zero sense of smell.

And yep, ask anyone who has been in lengthy combat situations or long hikes, etc. We can become impervious to what would be noticed by others. I’ve been in workplaces where workers became insured to occupational odors.

The issue here is passengers complained, crew members (and apparently “ground pounders” as well) verified and ultimately the Captain made a de ision - I’m sure with the awareness second guessing, investigation, negative publicity, etc. we’re likely.

I’m sure rare decisions are made based on personal biases, though after publication, investigation and even law suits from incidents of this type they’re rare and decreasing in number as airlines establish policy and train personnel. As a passenger, I’m generally comfortable when crew investigate and the Captain decides to have someone removed.

(I distinctly recall an in identnyears ago, when a very agitated man with apparent Tourette’s boarding with an escort loudly shouting “No! No! The bomb! The bomb!” as he was being guided to his seat. All the passengers in the DC-10 coach cabin heard him, and considerable discomfort was expressed. He also shouted he would behave as he and his escort were removed from the plane. I doubt he’d have been able to sit quietly, iirc MIA to SFO, or perhaps to DFW, for the entire trip, much less if we experienced turbulence, etc. Discrimination against a person with a mental - emotional disability in violation of the Air Carrier Access Act wasn’t an issue - extreme disruptiveness resulting in considerable passenger anxiety and discomfort was, as crew reported and the Captain determined.)