If it is done in the right amount and in the right way, it can fetch some rather interesting results- usually positive.
purchase hasn't arrived by eta.
instead of saying to the shipper, "bitch where's my shit at," "you cheated me and i am suing," or " gimme my money back you shyster," try saying "my shipment has not arrived yet and i was wondering if you could verify if/when it was shipped."
someone refutes your beliefs.
instead of saying to the arrogant little so and so, "fuck off, prick," "you're an ignorant little street rat, aren't you," or "your lack of decorum inspires me to drench your lawn in your blood," try saying "I am sorry you feel that way. You might benefit from knowing more."
The above is presented based on recent experiences and what a little tact and diplomacy fetched for results. Usually by not losing your cool, you will find that you benefit from a situation and might even get some support or friends along the way...