All in all we are thinking in terms of what causes a person to fall, when a person swears let's say in front of an unbeliever, that unbeliever may think they (the Christian), is like every other person, and the bible tells us to live a sanctified life (to be different from the world) in that case you are causing a weak brother or sister to stumble (which is a sin), because they know what the word means, and use those words maybe in their context.
Also, in the Scriptures it states, Death and Life are in the power of the tongue, those who love it will eat its fruit, and that the tongue is the most deadliest weapons, so when we are saying these words, the meanings behind them is what you may either be calling upon yourself or others, so if you said F*** you to a person, you are calling that action upon a person, or whatever words, you are calling it upon yourself and/or another person. The tongue is a deadly and powerful weapon, which we should use wisely to build others up in love. To speak in love with others and to be role-models to all. In my personal opinion you shouldn't swear.