Variable by base style. The contribution of non-Saccharomyces microbes should be noticeable to strong, and often contribute a sour and/or funky, wild note. The best examples will display a range of aromatics, rather than a single dominant character. The aroma should be inviting, not harsh or unpleasant.
Variable by base style. Clarity can be variable; some haze is not a fault. Head retention can be poor due to high levels of acid or anti-foam properties of some lactobacillus strains.
Variable by base style. Look for an agreeable balance between the base beer and the fermentation character. A range of results is possible from fairly high acidity/funk to a subtle, pleasant, harmonious beer. The best examples are pleasurable to drink with the esters and phenols complementing the malt and/or hops. The wild character can be prominent, but does not need to be dominating in a style with an otherwise strong malt/hop profile. Acidity should be firm yet enjoyable, but should not be biting or vinegary; prominent or objectionable/offensive acetic acid is a fault. Bitterness tends to be low, especially as sourness increases.
Variable by base style. Generally a light body, almost always lighter than what might be expected from the base style. Generally moderate to high carbonation, although often lower in higher alcohol examples.
A sour and/or funky version of a base style of beer.