Let's discuss whether one can definitively say that one wine is better than another. There will always be an element of the subjective in analyzing wine because people have different palates and preferences. So, does that mean there are no objective truths when it comes to wine? Are all things are necessarily subjective? Not really. Objective "truths" can be measured by applying agreed upon standards. In things that are not automatically quantifiable or easily measured, like beauty, we use a standard of fixed criteria to determine what is objectively "true." Why the quotes around truth? Essentially, we are making an approximation of the truth, which we can better judge with more knowledge, in the same manner as the prisoners in Plato's Allegory on the Cave. Now, certainly, these criteria may vary with societal norms. For example, a Rubens model would not necessarily be regarded as the height of beauty today. Notwithstanding that "objective" standards may change with the times, we apply the applicable normative standards to try to a mental checklist by which we can compare two things. Make no mistake, those with greater experience have a superior sense of what is comparatively "better" because they can consider more factors and, accordingly, describe to others why something has more value. On the other hand, if everything is subjective, then the value of everything is minimized. Red Skelton's clowns cannot be considered better than Picasso's ladies simply because someone likes them better without diminishing the value of all art. We are elevated by beauty and diminished by the regression to the mean.
Isn't that why we have critics for things like wine? They are presumptively the most experienced and, therefore, they can best judge one wine against another (in Plato's Allegory, they would be closest to the sun). Variation in judgments may exist because of externalities and general preferences. It becomes, then, our responsibility in relying on these critics is to try to calibrate our palates to theirs, mostly to narrow the inherent elements subjective preference. Another way to blunt the manifestation of the subjective, would be to have a panel in lieu of a single critic. When the panel is a number of experts, such as the Grand Jury European, the result may be compelling. When the panel is a bunch of amateurs, especially in the context of a blind tasting, the results are often absurd.