Robert Parker – is arguably the most influential wine critic in the world. Parker’s tastings are done in peer-group, single-blind conditions, meaning the producer of each wine is not disclosed at the time of tasting. The ratings reflect an independent, critical look at the wines. Some wines have a range of points ie (85-90) points – this is usually because the wine was tasted and scored before bottling and finishing (ie. in the barrel).

Robert Parker 100-Point Scale
96-100: An extraordinary wine of profound and complex character displaying all the attributes expected of a classic wine of its variety. Wines of this caliber are worth a special effort to find, purchase, and consume.
90 - 95: An outstanding wine of exceptional complexity and character. In short, these are 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 a soundly made. In essence, 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 deemed to be unacceptable.

The Wine Spectator – is a longtime advocate of the popular 100-point rating scale; wines are always tasted blind and tasters are told only the general type of wine (ie. varietal, region and vintage).  Ratings are based on potential quality on how good the wines will be when they are at their peak. 95-100 points would indicate a great wine for your collection and 50-59 would be considered undrinkable.

Wine Spectator's 100-Point Scale
95-100: Classic: a great wine
90-94: Outstanding: a wine of superior character and style
85-89: Very good: a wine with special qualities
80-84: Good: a solid, well-made wine
75-79: Mediocre: a drinkable wine that may have minor flaws
50-74: Not recommended

International Wine Cellar – scores are based on their expected quality during their period of peak drinkability. A “+” after a score denotes a wine that is likely to merit a higher rating in the future. All wines rated 90 or more are highly recommended additions to your collection; wines rated at least 85 are recommended bottles that should provide pleasurable drinking. Precise scores are provided only for wines in bottle; ranges are offered for unfinished wines.

International Wine Cellar’s 100 point scale
95-100: Extraordinary
90-94: Outstanding
85-89: Very good to excellent
80-84: Good
75-79: Average
70-74: Below average
<70: Avoid