The author addressed this issue in an article, explaining why the scale is dynamic and should be looked with some reserve and some care. Unfortunately every time some one googles his name and scale he just gets the scales and naively interprets them.
Well using his own explanation:
http://www.hificritic.com/colloms/sound.aspx
http://www.hificritic.com/colloms/ratings.aspx
This still doesn't really support his scale very well. His initial assessments were 0-10 with 10 being perfect. In time many improved products began reach 8 and then 9 regularly. So he expanded the scale linearly on the perceived improvement. Reaches near 100 now. Okay, so was his assessment accurate? Did so many products get to 9 of 10? If so how is the linear adjustment in relative terms now up to 10 times that amount. And if true as described are products better than perfect before, or is the scale now so divided we are talking improvements between 90% perfect and perfect expanded greatly. It would appear he is claiming to rate things in these percents or tenths of a percent even. I don't think the finest human ears are that stable from one day to the next. Sorry, not buying it.
MC was doing this in good faith, but I believe he has lead himself down the garden path quite a ways. And I still don't know if he means today's 99 is equivalent to yesterdays 9.9 or whether today's 50 is equal to the old 5 or is it halfway between 9 and 10 on the old scale. Again, there are simply too many problems with his scale. I don't know whether it is just a numerical version of saying I slightly prefer product A to B or whether it is an attempt to make his subjective assessments appear reliable on a genuine scale of some false precision. In years past I would have said the former though his writing in the last decade makes me think the latter.