For native Spanish speakers: Just how weird does it sound when a word has the incorrectly gendered article?

For example, if a person said "la perro" or "un banana." Surely the meaning is there because you see / hear the word but with the incorrect gender of the article does it sound very strange? And is this common when little kids are learning how to speak? As an English speaker whose language doesn't have gendered words it's an interesting thing to think about.