Nechesh, you may have a point (like the one on top of my head 

 ).  I think it is not rust but chemical discoloration that occurs with near full strength acid of this nature is used and not cleaned off well.  Nice greys and blacks though.
I also like Moro-maniacs (since I coined the phrase 

 ).
(Moron-ians indeed!... 

 ... 

 )