How many don't? More specifically: how many don't when blinded and not looking at their shiny baubles? Anyway, it makes sense to consider that such a general question comes from someone who listen to music using speakers, and not speakers themselves. The neurotic gear obsessed people probably already know what they want, and would add a bit more detail to the question.
Only when they're bad (inb4 circle of confusion).
Remains to be proved, in the case of people with normal/non-damaged hearing.
Your reasoning would be non controversial in an audiophile forum. I'm pretty sure preference does exist in the case of people listening to speakers, that's the entire point of the hobby, but not so much in the case of this other hobby called music listening.
People who put ketchup on everything they eat aren't gourmets, they're just ketchup fans.
Regarding - How many don't - I don't know as i'm almost certain neither do you. Pretty safe bet most people listen to music using speakers. Seems as if your trying to create controversy where none is needed.
Regarding - Only when their bad comment- Speakers ( plus the room ) are the final tool in the chain to produce the music we hear. Good or bad.
Regarding - Remains to be proved, in the case of people with normal/non-damaged hearing.- I' assume you meant remains to be proven. Talk with any Otolaryngologists and I'm sure he or she will confirm, people hear things differently, whether to hearing loss, normal hearing, extraordinary hearing, dry ear, fluid in ear, etc. All of these things effect the way you or anyone else interprets sound. Point is, just because you hear one thing from a certain speaker, they next guy may hear something else.
To your last point regarding my reasoning- My statements shouldn't be controversial on any forum. You can say what you like, science can say what is accurate, my point was and still is, regardless of either. People do have their own preferences especially when it comes to speakers. We do listen to music coming from the speakers.
While the science says a more flat response is correct, that doesn't change the fact that not everyone prefers a flat response. Think of all the bad measuring speakers out there. One example, the Klipsch ( heresy, cornwall, heritage ) speakers. While they are a nightmare with the measurements, yet they still seem to have loyal following of people who just adore them. Although most folks i know don't like them, they have a sound signature that some folks do prefer.
Which comes down to what i stated earlier, most people have their own personal preference when it comes to speakers. That's why when it comes to people asking for recommendations, I'm not sure how I can be wrong by telling someone the best advice is to go and audition them for yourself.
As to your ketchup gourmet scenario, that's just being silly. ( real men use mustard
) Who are you or i to say who is or isn't a gourmet because of whatever ingredient they choose to use. It's no different, when people start arguing over, what is an audiophile. Who cares? If someone enjoys and loves listening to music, want to call him or herself an audiophile, well then good for them. Whatever equipment you choose to get you there and accomplishes your goal of audio nirvana, in the end usually boils down to some form of personal preference. Neither science nor our ears are perfect. Measurements are great and all, but as alot of people would agree who have or use any type of room correction software tools, in the end a little user personal preference tweaking occurs.