Scum of the Earth

I spent the last week traveling around and I got to spend a good chunk of that time with my brother.  While I was there I noticed how frequently he used the phrase "the scum of the earth" referring to bicyclists on the road.  Now of course he said this because anybody that impedes his going super-sonic on any road is without a doubt missing from the deepest circle of hell.  Maybe Satan should be holding Judas in one hand and Lance Armstrong in the other…instead of Brutus.  (Just a joke of course…because whenever Lance races I'm sure those roads are shut down).  But, this term and how it was used made me wonder.  When someone is called 'scum', to me that means they are the lowest form of low…they are without any self-morality and are completely contemptible.  And, using my brother's logic, they are anybody that impedes your progress. I will take it one step further and assert that they can be those who not only impede your physical progress, but mental growth as well.  

I don't know why I felt the need to expand on this thought, but it clearly impacted me and caused me to think about the term and its place in the phrase.