Same problem, the actual range is 15-20 in .5 increments, smaller .points for the pretentious. The 20 point scale has components (colour, aroma, palate) that supposedly make it more consistent compared to the "pick a number" approach of the 100 point scale, but I think that's a fallacy.
All points-based systems have the same issues of pretending to show a precision that words don't convey and yet just end up as a marketing tool.
Compound that with the brevity of notes in such bulk publications as the Wine Companion, many of them are really quite useless in fully describing the wine. My monthly tasting group is usually supplied with tasting notes for the wines tasted single blind in sets of four, often from Halliday. In about 50% of the time the notes are not very useful in identifying the wine and often don't closely match the wine in front of us.
It's a bit long-winded and results in tasting notes presented in a formulaic fashion, but use of this sort of tasting sheet will always result in a note that covers all relevant aspects of a wine.
http://www.torbwine.com/images/Torb Tasting Sheet.pdf
All wine reviews have the same issues - it's the opinion of one person of one bottle at one point in time. Some reviewers obviously resonate more and more consistently with your individual tastes/preferences, they are the ones to identify and pay most attention to.
