Following on from the hubbub about producers objecting to criticism of their wines, it's worth considering if there can be consensus about what makes a wine bad. There are ostensible quality factors which are allow us to agree, to a certain extent, on objectively good quality - so if those same factors are not present in a wine, can we agree that it is bad?

Let's take BLIC as the starting point: balance, length, intensity and complexity.

Balance is undoubtedly an important factor in wine, and received wisdom suggests that all the main structural elements of wine (acid, alcohol, body, sugar and/or tannin if present) should be well integrated. This sounds like a technical matter, but it almost immediately involves subjective opinion. Many wine professionals think English sparkling wine is too acidic, or that 15% Napa Valley Cabernet is too alcoholic - but others find them perfectly well balanced. In such cases, personal taste will therefore dictate quality assessment. But while the astringent tannins of young Barolo or Pauillac cannot be described as balanced, the best examples will achieve harmony with bottle age - so in this case, experience is vital to make the correct judgement.

Length is more straightforward: a wine without persistence is surely lacking one of the defining features of good quality wine. But it's not unusual for two experts to disagree on how lengthy a wine's finish might be - especially if you then consider the impact of bottle variation on older wines.

Intensity seems to suggest that the more intense a wine is, the better its quality. However, there can easily be too much of a good thing. Wines that are heavily over-extracted might be highly intense, but if the flavour is too powerful it becomes overwhelming and lacks nuance. Even so, while we might agree that dilute wines are poor quality, and that certain styles of wine (eg Chablis or Muscadet) have merit in their relative restraint, the best fine wines (eg Chablis Grand Cru or Muscadet Cru Communaux) do have intense flavour concentration.

Complexity, like length, seems a no-brainer: simple wines are not as good as complex ones. Yet personal preference inevitably plays a part here too. Are the animal aromas of wines with high levels of 4-EP from Brettanomyces a good thing or a bad thing? Again, it's entirely normal for experts to disagree as to whether the complex flavours of a wine contribute or detract to its quality level.

Added to these four factors, we might also consider typicality. Since wine is so varied according to its grape variety and origin, a sense of authenticity is part of what makes it great quality. This is immediately complicated by blind tasting, where atypical wines might be assessed favourably in their own right, but less favourably if they don't comply with their expected style - most people wouldn't want obviously oaked Riesling, for example (but it certainly exists, and could easily fit  the quality criteria stated above).

This debate has been triggered by wine producers objecting to the ability of critics, which inevitably includes their assessment of wine quality. But quality is not an objective, measurable component that everyone can or should agree on. Certain factors might seem unarguably 'bad' - a very short finish, dilute flavours or a total lack of complexity, for instance - but beyond that, it ultimately comes down to a matter of opinion.