Which of the following should never be done when serving draft beer?

When serving draft beer, it is crucial to maintain cleanliness and quality standards to ensure the best drinking experience. Allowing the faucet to contact the beer or the glass is considered poor practice because it can introduce contaminants into the beer. The faucet can harbor bacteria, yeast, and other undesirable particles from previous servings, leading to potential off-flavors or spoilage of the beer. This practice compromises the integrity of the beer being served and can affect the overall quality and taste.

On the other hand, using a clean glass, pouring at an angle, and pouring directly from the tap are all essential practices that promote a good serving technique. A clean glass prevents any residue or flavors from previous glasses from interfering with the beer, pouring at an angle helps create a proper head and reduces excessive foam, and ensuring that the beer is poured directly from the tap into the glass ensures that the beer remains clean and fresh. Thus, avoiding contact of the faucet with the beer or glass is key to maintaining the quality of draft beer served to customers.