Frodo,
I think everyone else has done a great job of explaining the reason some cuss words are viewed as sinful and that being due to the angry intent. As well as touching on the abuses of God's name that are sinful. And I see you are still a bit confused and I think I may see part of the reason why. There are some words and their uses that aren't taking the Lord's name in vain and are not outward signs of anger, but they are sinful for a different reason and I don't see that these words have been properly addressed.
The list of cuss words includes many words concerning bodily functions and body parts. None of those functions or parts are sinful, in fact, some of those actions are one of the most wonderful gifts God has given us, the ability to fully give ourselves to another human being in love and cooperate with God's will to create a new soul. A marvelous, miraculous gift. However, those words tend to be used to strip this God given gift of everything loving, pure and meaningful and turn it into a base, lustful act of the flesh without meaning and devoid of love. That is a sin against God's creation. And that is why some of those words are so offensive to Christians, they take a perfectly loving act and remove God, love, and meaning from it.
So, you may not be thinking in the context of what the word means, or using it in anger and your use may not even be in the context of the act or object it refers to but others around you may interpret it differently and you ignoring the meaning may be viewed as demeaning the act and demeaning God's creation. That's why at best it is rude to use those words in public, you can't know how the use of the word will be viewed by those around you and it may be demeaning something sacred and treasured to them. If you know that you are surrounded by people that share your values or will completely understand the context and meaning of the word to you and not take offense, it may or may not be sinful to use certain words. But the root cause for the response you get goes back to what the words are referring to and how they devalue human life and acts that are gifts from God when probably ordered in life.