Hence why I will harp incessantly w.r.t. acoustics and take with a grain of salt many audiophile claims, especially after seeing listening rooms. Totally laughable when they then make claims about other people's systems not being resolving enough. But I digress.
I'm with you. What I think I have observed is
a - Self delusion
b - A large variability in the ear brain mechanism being able to filter out room acoustics.
Based on what I know about machine learning, and neural nets, and observations at shows, I believe some listeners can pick out some delicate traits about system despite absolutely terrible rooms.
I personally, cannot. As studies in learning and acoustics have shown, filtering out noise is energy consuming. Your brain works harder in an acoustically messy environment and I absolutely feel it.