In fact , so much so , that the lines contained large chunks of yeast and protein . And it wasn't just my unfiltered - Belgian - beer line . The lines for Stella Artois and Miller Lite , if not chunky , were also filthy . I told the owner that he needed to clean his draft beer lines , and pronto . 
Question: Why did the lines contain large chunks of yeast and protein ?
Because the lines were dirty .