In reply to Rich W Parker:
I recommend Julia Boyd's book Travellers in the Third Reich - it explores this very question (in 400+ pages). It focuses on how, mostly British, travellers to Germany experienced the rise of Nazism in the interwar era. It's based on first hand accounts, so letters, diaries, etc. of those we were there at various points during the interwar era. It's a long, but interesting, read.
She writes that by the end of 1936 it would be near-impossible for any Brit to be ignorant of the Nazi brutalities that were already commonplace, but that many continued to holiday there regardless.