Here's the sign greeting customers at Southwest Shooting Authority in Arizona:

The sign has caused some obvious controversy.  But why?  What's the big deal?  Plenty of businesses have signs that let customers know they reserve the right to refuse service. 

The real question is wether or not it's a good business move.  For a big time restaurant, probably not.  For a gun store whose business probably doesn't come from many Obama supporters anyway, absolutely.