Have you noticed that it is the same when you speak.

If I want to make a complaint about something I never swear. I will e-n-u-c-i-a-t-e very carefully (to make sure the person understands every word), in a tone that makes it clear that they DO NOT want to make me mad. I am also told that I usually sport a beatific smile that makes it that much more scary. It works quite well.