Sommelier Madeline Puckette, author of Wine Folly, asks (in her email newsletter): "Is There Such Thing as Good Cabernet Under $20?) Her conclusion, after tasting three candidates priced at $15 to $20, is "no." From my experience, I agree. And that is the main reason, I rarely drink or review New World Cabernets here except for a few bottles from the cellar that I may have cost me $10 or $15 back in the 1980s but are worth much more today.
The bottles sampled by Madeline Puckette were the 2015 Louis M. Martini Sonoma County Cabernet, the 2016 J. Lohr Seven Oaks Estate Paso Robles Cabernet and the 2016 Smith & Hook Central Coast Cabernet. On examining the color, she found that they all "looked amazing"--maybe too amazing. The were all very dark with a level of color extraction that one would not expect from wines at this price level. "No one has ever admitted to using wine grape color concentrations, so I was unable to make a conclusion." There are, of course, rumors in the trade.
The three wines also "smelled pretty good"--but only the Louis Martini actually smelled like Cabernet, albeit a little overripe. As for taste, they all had "an explosive zing of sweet-sour acidity that tasted like Sweetarts (the candy)." She concluded that they had all been acidified--a common practice with warm-climate New World reds.
The Cabernet grape is highly tannic--one reason that it has a track record of producing great, ageworthy wines in the Napa Valley as well as Bordeaux. But tannins can taste bitter in a young wine, and these wines had somehow managed to get rid of or hide the tannins. Consumers, of course, appreciate the smooth mouthfeel, but anyone who has tasted a fine, well aged wine knows that it is better to tame the tannins with appropriate time in the cellar rather than technology.
My conclusion (and hers) is that most New World Cabernets worth buying or drinking will cost you more than $20 and probably require at least several years of aging. The rest are manufactured for mass consumption.
The good news is that there are many very good artisan wines for under $20--wines from special micro-climates and vineyards produced by winemakers who believe that good wines are made in the vineyards and not the chemistry lab. These are the wines that are my focus for buying, drinking and reporting.