When will we ever hear turntables demoed fairly?

Reviews are essentially nonsense,hyperbolic drivel that is designed to really do one thing.Keep the hamster on the wheel(that's you).If technical data were the sole criteria we wouldn't have this highly variable mess of designs.But it's not because there is an aesthetic injected into designs.Well tempered turntables vs technics direct drives just to name one large differential in design.Add the impossibility of fair AB comparisons and it's just a hot mess of cash flying every opinionated which way.Just one man's opinion.

We'd have the same problem if every dealer were 100% altruistic. A big limitation of the scientific method is that you can change only one variable at a time. Which one would it be? Would we be comparing turntables, tonearms, or cartridges? What about shelves and platforms? What about inherent compatibilities and incompatibilities (e.g., arm/cartridge resonant frequency matches, best turntable mat for a given design, etc.?) What if you use just one turntable to try out multiple cartridges? One or more may simply be a better resonance match than the others, and one may get (by sheer luck) a better setup with optimized SRA, VTF, and overhang. 

Like pixelriffic, I also worked in a high end audio store and visited many others. In my case it was during the "golden age of hi-fi" in the mid-70s when the LP reigned supreme. This was when audio stores were teeming with people looking for turntables, receivers, and speakers. But I don't remember any store having multiple turntables, tonearms, and cartridges for audition. This function was handled by the audio magazines of the time, which might occasionally have cartridge comparisons, all done on the same turntable, possibly adjusting for tracking angle and VTF, but probably not SRA. 

Most serious turntables today have integrated headshells. Every cartridge swap is a tedious operation and downright perilous when hurried, often vulnerable to 4- and 5-figure catastrophes if an unprotected LOMC is dropped. What store could afford to reserve an audition room for a day to audition a few expensive cartridges? Such a customer could more easily afford to sell his barely used cartridges on Audiogon and try some more in his quest for the ideal cartridge than the store could afford such an extended and labor-intensive comparison as a standard service.

Still, we should be able to compare a few table/arm/cartridge set-ups with the same amp/speakers and comparable if not necessarily the same phono stages.

That still renders the results misleading. System matching is the crucial element in getting component audio to "sing." Sources, preamps, amps, speakers, and of course the cables in between each. But LP decks are a whole different can of worms. Digital sources generally have nearly the same output impedance and output voltage. You can compare players and music servers pretty much with impunity. You can even then leave these players in place and swap various DACs in and out to look for further improvements.

There is no such equivalent with LP decks. They are truly "analog" electromechanical devices which retrieve the physical source at a microscopic level (the record groove). There's no way to perfectly adjust every aspect of VTF, VTA, azimuth, and tracking angle for every cartridge, and even if you could, there could be various levels of damping fluid for tonearms so equipped, various mats that work well with one but not another, footers, platforms, power cords, cabling. And if you change the phono stage, that by itself doubles the complexity with each swap.

inna:

So John, what do you suggest?

I was trying to answer the original question, "Why don't we hear turntables demoed fairly?", not to provide a solution. Ironically, the solution is probably the foundation of Audiogon itself. Audiogon was a high end classified ad website before it had forums and member system profiles.

Because there are so many interdependencies in an LP playback system, it is better to evolve the system over time, making one change at a time, do in-home demos where you can (e.g., phono stage, mats, cables, etc.) and when you get a bad match for a cartridge, put it up for sale. If it's a desirable cartridge with minimal time on it, you might recoup 80-90% of the purchase price. Audiogon classifieds offer many such items.