Why is whiskey gold or brownish?

Answer 1

Alcohol, like other volatile liquids, can break down when exposed to light. Colored bottles, usually brown or green, prevent much of the light from affecting the alcohol, but allow the consumer to still see the amount of product left in the bottle.

Vodka, unlike whiskey, is usually sold in clear bottles, due to marketing concerns. Vodka producers want to impart clarity as a selling point for their spirits, so the bottles are clear, but vodka is just as susceptible to alcohol loss as other liquors. When light breaks down alcohol, it creates an off-flavor in the spirit. It does not, however, make it any more dangerous to drink than it was when first bottled.

Answer 2

The oak barrels.

See similar question "Where does whiskey get it's colour from?"

Answer 3

Not all of them do.