When it comes to foul language, there is a saying: "Do you kiss your mother with that mouth?" I think a more appropriate saying would be "do you praise your God with that mouth?" I am not the first to make such a point. In James 3:9, we read that with the tongue, "...we bless our God and Father, and with it we curse men, who have been made in the similitude of God."
The full passage (v1-12) describes the power of the tongue. Effectively, James says if you can control your tongue, you have great power indeed, but if you do not control your tongue, your tongue will control you.
Jesus makes a similar point. In Mark 7:20, He says "What comes out of a man, that defiles a man." And again in Matthew 15:11, Jesus says "Not what goes into the mouth defiles a man; but what comes out of the mouth, this defiles a man." (Both accounts describe the same event). In other words, you can eat what you like and be clean, but the moment you say a curse word, you may as well have cursed God.
Now, I can't cast any stones. This is as much self-criticism as it is seeking to edify the Church. But for the sake of our Lord, each of us needs to make every effort to ensure that if we can't say anything useful, let us say nothing at all.