What should be checked if the line or faucet is dirty in a draft system?

Cleaning the line or faucet is essential in maintaining a draft beer system because the quality of beer can deteriorate due to the buildup of residue or contaminants. Over time, yeast, protein, and other materials can accumulate in the lines and taps, leading to off-flavors, odors, and a negative overall drinking experience.

Routine cleaning of the draft system ensures that the beer served is fresh and flavorful. It's important to follow a regular cleaning schedule to prevent this build-up and to maintain the integrity of the beer's taste and quality. This allows for better beer presentation and helps in reducing potential bacterial growth which could affect the health of anyone consuming the beer.

While replacing the keg or changing the CO2 tank may address some issues, they do not resolve the problem of dirt or buildup within the lines or faucet. Lowering the temperature may affect the beer's serving characteristics but does not address the underlying cleanliness of the system. Thus, focusing on the cleanliness of the line and faucet is the most effective and necessary step to ensure optimal beer quality and system performance.