How do you know if wine has gone bad?

Question

Which smells indicate that wine/beer is bad?and can it have any negative effect on health?

Answer 1

Here is a list from the Wine Faults Wikipedia page. These faults, for the most part, will not do any harm when they are in wine (they aren't strong enough) They just taste bad.

Acetaldehyde Smell of roasted nuts or dried out straw. Commonly associated with Sherries where these aromas are considered acceptable

Amyl-acetate Smell of "fake" candy banana flavoring

Brettanomyces Smell of barnyards, fecal and gamey horse aromas Cork taint Smell of a damp basement, wet cardboard or newspapers and mushrooms

Butyric acid Smell of rancid butter

Ethyl acetate Smell of vinegar, paint thinner and nail polish remover

Hydrogen sulfide Smell of rotten eggs or garlic that has gone bad

Iodine Smell of moldy grapes

Lactic acid bacteria Smell of sauerkraut

Mercaptans Smell of burnt garlic or onion

Oxidation Smell of cooked fruit and walnuts. Also detectable visually by premature browning or yellowing of the wine

Sorbic acid plus lactic acid bacteria Smell of crushed geranium leaves

Sulfur dioxide Smell of burnt matches. Can also come across as a pricking sensation in the nose.