stereo system a is accurate--fact
stereo system b is inaccurate--fact
so far, there would be no disagreement if the facts were established properly.
to say stereo system a is better than stereo system b is illogical and only an opinion.
Mrt, I did not get your email. BTW your conclusion above is not logical. System A in the example above is logically the better. This is because 'accurate' is deemed by the world at large (through agreement) to be better than 'inaccurate'.
Many things exist out of agreement. Money is a good example- the material of a $100 bill are worth marginally more than a piece of paper the same size; we give it the value out of agreement. Stop signs have their value out of agreement as well.
So logic dictates: if accurate is better than inaccurate, and system A is accurate and system B is not, then A is better than B. You may attach whatever personal meaning and value you wish to the contrary, but usually its best not to make those feelings public.