I'm going to take a shot and say that the point of the Sick cover was to be "I am your teacher, and I will tech you the technical, and the sick". I can see a clear idea on the cover, but I don't think I could figure out what type of music I was going to hear by looking at it. It could be anything really... I think the nonsense on the blackboard changed the tone a little bit.
But again, did Killer's cover really represent the sound of the album?