Bad or just immature?

Basically, in my opinion, no good wine tastes bad at any point in its life. Certain ageworthy wines may be tannic (astringent) and closed in their youth, but even then, they'll show a presence of fruit and overall balance that indicates quality.

As a generalization, only a fairly small amount of all the world's wine requires aging, and you can tell that without even opening the bottle. The better Bordeaux, a few of the finest Burgundies; the top California Cabernet Sauvignons and their equivalent from Australia: These are the wines meant to be cellared for years before you open them. But just about any white wine and most of the reds -- totaling probably 95 percent or more of all the world's wine production -- will never be any better than it is upon release, and it's all downhill from there.

A wine that's light, fresh and fruity is obviously ready for drinking now.

A wine that's dank, brown, sherrylike or (rarely in modern times) vinegary is over the hill, dead and gone.

The relatively few wines in-between, the ageworthy wines that are too young for drinking now, will generally seem "tight" and "closed," that is, not showing much fruit or complexity; but there won't be any off or unpleasant flavors hiding behind the tannin, just good clean fruit. Sometimes leaving the wine in the glass for an hour or two, or leaving the wine bottle open overnight, will accelerate the aging process and give sort of a weak preview of what the wine's future holds, but this isn't really the recommended way to age your wine by brute force!

As for books, most of the good overview books like Hugh Johnson's Wine Encyclopedia will touch on the aging process; one very good book devoted entirely to the subject is "Vintage Timecharts," by the British wine writer Jancis Robinson.