What is one reason a strong mixed drink may impair a customer more than expected?

A strong mixed drink or cocktail may impair a customer more than expected because it can contain more than one standard drink's worth of alcohol — for instance, a cocktail with multiple shots of spirits. The customer may count it as a single 'drink' while actually consuming two or three standard drinks. Sweet mixers can also mask the taste of alcohol, leading customers to drink faster. Servers should be mindful of drink strength when monitoring consumption, since the number of glasses can understate the actual alcohol intake.