What does it mean when someone Don't snarl at bank tellers. i don't get it?

Question

What does it mean when someone Don't snarl at bank tellers. i don't get it?

Answer 1

Don't snarl at bank tellers. It is useless: They usually don't have the power or authority to fix things for you, so it won't get you what you want.

And - they may *know* who does have that authority or power, but why would they share that information with someone who is mean to them?

Answer 2

Perhaps it means they like bank tellers. If they don't snarl at them, they must be more tolerant than you (assuming you snarl at bank tellers).