They should have a glowing orange-brownish color like the whiskey in the game, as scotch is a type of whiskey. It even shares its world model with "large whiskey bottle," a clutter item that bears "Scotch" on its label but can not be consumed.
Scotch can be obtained freely from Dukov when asked, "Hey can I have some of that hooch?" He then encourages the player character to take a bottle of scotch from the upstairs cabinet.
Gob offers kind player characters a discount on the scotch he sells.