not really related to audio, but I can give this little bit of history that I encountered that shows the folly of complete reliance on your senses:
for anyone who knows anything about firearms, you would know about the M1903 Springfield rifle. good rifle, however a number of earlier production rifles had some metallurgy issues (generally not serious since those rifles in service would have to first pass inspection and minimum standards, real problems only arise when its combined with other issues like say, bad ammunition).
the cause? heat treatment of the receivers earlier on, at least at the Springfield Armoury, was done by eye; the craftsmen responsible would judge the temperature by looking at the colour of the metal. the problem with this was that there were windows in their workspaces, which let in light which naturally affected the perceived colour of the metal those craftsmen were working on. temperatures were off by 200 degrees Celsius at times.
the metallurgy issues were solved with the installation and use of temperature gauges for later production of the rifles.