I've heard that in Germany or Switzerland dialects differ very much, and you can tell very quickly where someone is coming from. But I've always been told this by linguists so I have no idea whether it works for ordinary people too.
In my language we have few dialects, but all I can tell is speaking one of them, I can't identify which. And I would expect it to work like that for most people, honestly
But maybe I'm wrong?
(YOU is all caps, because I wanted to make it clear, that I'm talking about you, the reader, ordinary redditer, not about general possibility of knowing dialects)
Edit: honestly it's crazy that everyone says "yes, obviously", I was convinced it was more like purely theoretical, only distinguished by enthusiasts or sth. Being able to tell apart valley or cities seems impossible