Have you ever went to a bar and ordered a beer that you know you love, just to be disappointed with the end product in your glass? There are many different things that can cause a beer to taste different from place to place, but chief among them is dirty beer lines. Dirty beer lines can cause infections in your beer and result in various off flavors; diacetyl is a common infection caused by dirty lines and imparts a buttery or butterscotch flavor.
So what can you do to prevent this from happening to your kegged beers? Having a consistent cleaning schedule for your kegs and beer lines is an important part of having your beers taste as good as possible. The easier it is to clean your lines the more often you will do it, and your beers will taste better as a result.