To talk about this stuff we should really make clear the difference between profanity, cursing, swearing, and vulgarity.
Profanity is when you use the Lord’s name in vain, or make references to religious subjects in a sacrilegious way. This is obviously sinful, and it certainly is something I avoid with an almost paranoid level of care, and it really bothers me when I hear people use such language.
Cursing is when you use profanity in a directed way at someone, and this is even worse than profanity by itself. Perhaps you use the Lord’s name in vain, but then you also commit the sin of wrath. Cussing, by the way, is just an Americanism, the etymology is the same as cursing.
Swearing is when you make an oath of some kind. People should be very careful that they only make good oaths, and then not break them. An example of good swearing would be what a person does when they get married and say their wedding vows. It only becomes bad if they violate those vows, or made them in bad faith (not actually believing in the Sacrament of Matrimony, for example). Another example would be to swear on a Bible that your testimony in court is going to be truthful, but then if you bear false witness that’s certainly sinful. Swearing to do something evil, or basing an oath on something evil, of course would also be sinful. This is another one for me that I am really careful about, and it also really bothers me when people swear casually about or on things they shouldn’t be.
Vulgarity, though, is simply crude, lower-class vocabulary. These would mainly be your scatological and sexual terms, and these terms especially change over time and even vary from culture to culture. If you use them in a wrathful way, that’s sinful. If your use of them hurts others, or leads them to sin, that’s sinful. The Bible does warn us that we will be judged for our words. We should be mindful of what we say, and how we say it, but the Bible doesn’t have a list of no-no words we should never speak and I personally don’t believe there is any such thing as a “bad” word. What matters is the intention and the consequences of our words, whatever those words are, and whether we are building bridges to other human beings and loving them, or tearing those bridges down.