If it's a 20 point scale, then it's even worse, because raters can't mark the same wine twice with the same score when tasted blind. So their margin of error is even larger if it's effectively a 20-point scale.
I know this also from the whisky raters who pretend they can mark out of 100.
This, apparently, is the Parker model...
96–100 An extraordinary wine of profound and complex character displaying all the attributes expected of a classic wine of its variety. I think wines of this caliber are worth a special effort to find, purchase and consume.
90–95 An outstanding wine of exceptional complexity and character. I consider these terrific wines.
80–89 A barely above average to very good wine displaying various degrees of finesse and flavor, as well as character with no noticeable flaws.
70–79 An average wine with little distinction except that it is soundly made. In short a straightforward, innocuous wine.
60–69 A below average wine containing noticeable deficiencies, such as excessive acidity and/or tannin, an absence of flavor, or possibly dirty aromas or flavors.
50–59 A wine I deem unacceptable.
Anyway, sorry if I moved this off-topic a bit...