It just comes down to manners. I bored many a person while learning to play, but playing with others is the best way to improve. Were you perfect when you started out?
Unless someone asks you for help or advice, don't offer it. If you end up pissing them off, they'll assume that nothing you say is worthwhile anyhow.
...And... if someone is "getting it wrong" that could be their interpretation of the song. Isn't that what the folk process is all about? I'm sure their used to be many of us white folk who used to think that "blue notes" were wrong. But they sure do sound cool.