I have no answer to that except to say they must be blind in some artistic sense. I too have come across this many times. Because of this, when I first visited Japan 25 years ago I visited many places before choosing where to train. I am now back in Japan again - as of last week - searching.
I have been involved in various sports (plus coaching) since a young age and have always followed the skill.
I see where you are coming from Rupert, but being able to tell if a martial art is bullshido or legitimately good is a skill. While some people might know what they are looking for I would wager the majority of people need some guidance if this was not the case then the problem of Macdojos would not exist. Aikido has so many different styles, it's not always easy to find what your looking for because non are "bad" they are just tailored to different people. What I look for is something that is a little more brutal, no nonsense, I'm not a big fan of styles that over exaggerate the movements and focus on internal energy. That being said and one of the reasons I've been asking questions is im also big on legitimacy which means being able to trace where my instructor came from in his journey.
While I think most people are able to tell if something is bunk, when your comparing two good dojos, its not always easy to tell which dose it best. And I nitpick a lot.