Sorry this reply is so late in coming.  I'm just getting to the old
discussions.  I don't know if Twain's depiction of Americans is the first
Ugly American but it does indeed fit the bill.  There is one scene in the
book where a self-important American insists on wine for dinner and says he
always has wine at home, etc.  being rude and loud.  It would describe some
people accurately today also.

Jerry O'Brien