Wine club members may have noticed that I don't include scores in any of my tasting notes that come with each wine. That's because I find it much more helpful to provide descriptions of the wines, where they come from, who makes them, and how they're made—because that's what you're tasting in the glass, not a number.
But why do critics use scores to assess wine? Scores function as a simple shorthand for quality without consumers having to read too much detail before deciding whether to make a purchase. Therefore, they can serve a useful purpose. However, there are so many different scoring systems that they become a confusing distraction; also, an over-reliance on scores doesn't point consumers to the wines they may actually like.
different scoring systems
Italy's main wine journal is called Vini d'Italia, published by Gambero Rosso, which rates wines by bicchieri or glasses (literally "goblets"). Tre Bicchieri is what the best wines receive; the next level is two glasses; then one glass; and then none. It's quite a simple system, and it's also less dogmatic than points-based scores. Wines can receive three glasses irrespective of price as long as they are exceptional in their category. In normal times, Gambero Rosso organizes a Tre Bicchieri international tasting of the three-glass wines so the scoring system is a good way of promoting Italy's best wines. (In fact, the tastings are starting up again across the USA—well worth attending if you like Italian wine.)
In France, the 20-point system is used as it was historically in the UK—Jancis Robinson still uses it and Decanter magazine only stopped a few years ago. To a certain extent, I like this system as it's not too histrionic. At the same time, it's misleading. The scores only really start at 10.5/20, with half points awarded thereafter, so it becomes a 20-point system within 10.5-20. It can also be a little too undramatic: 14.5/20 perhaps doesn't express the fact that it's a score for a perfectly good wine.
The most famous and widely-used scoring system is the 100 points created by Robert Parker and his magazine The Wine Advocate. It's become so widespread it causes as much controversy as it does support. Major publications such as Wine Spectator and Wine Enthusiast use it, to the point that scores make up the majority of the copy.
Robert Parker came to fame in the 1980s based on his newsletter which he mailed to subscribers, with the 100-point system used to rate wines. This was part of a trend in the States—Michael Lewis's book Moneyball records how Bill James's newsletter for fantasy baseball players came to influence the industry itself. Similarly with Robert Parker, who was a lawyer but became one of the world's leading wine critics.
Despite its universal use, there are many problems with the 100-point system. For a start, it's not actually a 100-point system, as it starts at 50 points. Furthermore, any wine rated below 80 points isn't considered drinkable. So, in reality it's a 20-point system like the French use, just with bigger numbers.
The 100-point system has also created an image problem for wineries, as any wine scored lower than 90 points is considered inferior—harsh on a good wine that's scored 89 points based on the opinion of one reviewer.
And then there's the 100 points themselves. In the 1980s, Robert Parker only gave 100 points to 19 wines; now, they're everywhere. This diminishes the impact of getting 100 points. It also means that winemakers chase 100-point scores by making big, full-bodied, high-alcohol, oaky wines that all taste the same but get the points. A system which was designed to aid the consumer has ended up pigeon-holing them into a small category and limiting their choice.
Despite the usefulness of scoring systems, for me it's all in the words. Some reviewers you may trust, others you may dislike. But take time to read their words—or to listen to the words of the retailer in the local wine shop. Or, indeed, heed the choices of blackpoolmatt's wine club! Ultimately, though, it's only your opinion that matters.