I was speaking to a man in the hardware store yesterday about moving to Wales. He lived in Ceredigion for a while, years ago. He said, "They don't like the English in Lampeter; they switch to speaking Welsh when you go into a shop."
That has never happened to us. As a learner, I want to hear people speaking Welsh, to practice my listening, so I know that people speak both Welsh and English. People are friendly (or not), just like anywhere else.