Sour/ Acidic: Excessive tartness in aroma and flavor. It can be clean (lactic acid) or sharp vinegar-like (acetic acid). PH below 3.0 is a sign that ethanol was oxidized to acetic acid and there is probably no recourse. At mild levels, pH (especially in wine) can be altered by the addition of some Calcium Carbonate (food grade chalk powder CaCO3). Vinegar CH3COOH in Latin means sour wine, which can be a reflection of how common this problem is.
If too much acetic acid is there, we will get a burning sensation in the nose, which is not desirable. In some beers like Gose, Wild Ales, Weise, and Sour Beers, a slight amount of tartness is desirable. However, do check the mashing process if the wort is getting sour. At low levels, it is often hard to distinguish between acetic acid and lactic acid sourness. Here, the smell comes handy. Lactic acid has no smell but vinegar has a distinct smell of nostrils burning.