There is no doubt that a virtuous person does not find it easy to utter obscenities lest he or she expose him/herself to the Wrath of Allah The Almighty and disgrace in the eyes of people. Although vulgarity is certainly dispraised and forbidden, foul words indeed abound.
Motives behind this behavior

Obscenity originates from wickedness and ignobility. It is either motivated by the intention of harming others or is a habit acquired from socializing with evil and debauched people, who are accustomed to insulting others. Whatever the case, Allah The Almighty has forbidden crude language in the verse (which means): {Allah does not like the public mention of evil except by one who has been wronged. And ever is Allah Hearing and Knowing.} [Quran 4:148]
Moreover, in His Book, He illustrated obscenity as characteristic of hypocrites, describing their conduct with believers, saying (what means): {But when fear departs, they lash you with sharp tongues, indisposed toward [any] good.} [Quran 33:19]

A believer does not imitate the insolent and crass people, preferring to stick to chivalry for the sake of preserving his or her honor. It was said in this regard, "Tolerating an abusive man is better than being like him and forgiving the ignorant is better than copying him."
Examples of obscenity

There are many situations and times when people of weak faith and bad manners resort to vulgarity. Imam Al-Ghazaali exemplified that by saying: “Situations of obscenity are various. They can generally be limited to any state that a person feels ashamed to overtly divulge. In this case, explicit words are considered obscenity. Therefore, one must discuss such issues in vague terminology.” Most of the relevant examples would be those concerning sexual intercourse and its related matters. While wicked people employ graphic and crass words when speaking about this, the righteous avoid such crude language and express themselves with figurative speech. Are we not aware that even Allah The Almighty spoke indirectly about sexual intercourse, mentioning instead, words like touching, entering with [women] and companionship?

There is also obscenity in making remarks about women or defects in men that they may be ashamed of, such as a limp or baldness. Any such comments, if necessary, should not be explicitly referred to.

The Prophet, sallAllahu ‘alayhi wa sallam, classified obscenity as a branch of hypocrisy and said, "Indeed, Allah hates the indecent and obscene person." Moreover, he, sallAllahu ‘alayhi wa sallam, mentioned that vulgarity leads to Hell, when he said: "Modesty is from faith, and faith is in Paradise; [whereas], obscenity is from severity, and severity is in Hell."

Please note that crassness is also to use names of animals to describe people. Imaam An-Nawawi said: “Among the vilified words which are usually used is a person saying to his enemy, ‘O donkey; you goat; you dog’, and the like. It is ugly to utter these expressions because they are lies and harmful to others.”

Dear brother, the Prophet, sallAllahu ‘alayhi wa sallam, even forbade abusing roosters, when he instructed, "Do not insult the rooster, for it wakes [people] to perform prayers.'' Bearing this in mind, could it be appropriate to affront people who bear witness to the testimony of truth [i.e., Muslims]?

The admonition of the righteous predecessors

Our forefathers from the Companions and their successors were the farthest people from obscenity and indecency. They seriously warned others against this great evil which originates from lack of faith.

‘Abdullaah ibn Mas‘ood, may Allah be pleased with him, said, "The most wicked trait a believer may possess is vulgarity." Similarly, Al-Ahnaf ibn Qays, may Allah be pleased with him, said, "I will tell you about the worst of diseases: the crude tongue and bad morals."
That is why, when Abu Ad-Dardaa', may Allah be pleased with him, saw an abusive woman, he remarked, "Had she been dumb, it would have been better for her."

We supplicate to Allah The Almighty to purify us from whatever displeases Him; and may peace and blessings be upon the Prophet Muhammad, sallAllahu ‘alayhi wa sallam.