The nicest were Japanese. Once I was lost - I had my kid with me and he wanted to use the restroom. I asked a shop clerk where the bathroom was but she didn’t speak any English. So I drew a toilet on a piece of paper. She left her shop and walked us to the bathroom. This was extremely nice of her.
The rudest shopkeeper award - in comparison - goes to Austria. When I was looking at things in her shop, she stood right next to me and immediately straightened every single object I touched. How strange.