Having recently seen the film "Lincoln" I thought I would check out this (fairly) well known expression.  When I was young it was quite common to hear "His name is mud," or "Your name will be mud when they hear about this,"etc.  What it means is that someone is in some kind of disgrace or is unpopular.  

Now, the story goes that this expression started with Dr Samuel Mudd who gave medical assistance to John Wilkes Booth in 1865 after Booth had broken his leg while escaping after shooting the American president Abraham Lincoln.  Lincoln was a great man ("government of the people, by the people, for the people") and revered by Americans.  For his actions, Mudd was immediately reviled and accused of conspiring with Booth.  He was later pardoned.

You can see that it would be easy to attribute the origins of this expression to American feelings towards Mudd, but "your name is mud" can be found in a dictionary of slang from 1823, and has its origins even earlier (probably C16 or C17).  It didn't take people to associate a lowly worthless substance like mud with other people.  Never mind, try to see the film - it's great.