What type of vermouth is used in a Perfect Rob Roy?

In a Perfect Rob Roy, the correct type of vermouth to use is dry vermouth. This cocktail is a variation of the classic Rob Roy, which is essentially a Manhattan made with Scotch whisky instead of bourbon or rye. The term "perfect" in cocktail nomenclature typically indicates that both sweet and dry vermouth are used in equal proportions.

In the case of the Perfect Rob Roy, the dry vermouth serves to balance the richness of the Scotch whisky and provides a more nuanced flavor profile. The combination of the dry vermouth with a splash of sweet vermouth contributes to a more complex and sophisticated drink, which is different from using solely sweet vermouth, which would give a much sweeter flavor.

Regarding the other options, sweet vermouth is commonly used in traditional Rob Roys, but for a Perfect variation, the emphasis is placed on dry vermouth to achieve that perfect balance. Bitter vermouth is not a standard type of vermouth used in cocktails and does not typically complement the flavor profiles of whiskies effectively. Red vermouth usually refers to sweet vermouth and, while it can be used in other cocktails, it would not align with the definition of a Perfect Rob Roy. Thus, dry vermouth is the ideal choice to create the intended