My question is: what makes a swear-word/curse/cuss offensive?
I submitted to a friend that in order for a word to be offensive three criteria have to be filled.
1) The speaker must utter the word with the intention to offend.
2) The speaker and hearer must both be aware of the background context of the word as an offensive word.
3) The hearer must hear the word and react; taking offence
The justification for this is that a word is just a sound and that many languages use sounds that in another language are curses. It is irrational to take offence to a sound if the speaker is ignorant of it's vulgar connotations.
Without a shared contextual understanding of a word's history as offensive, a speaker seeking to offend through uttering a word (without using other signs of contempt or emphasis) is just making a sound to the hearer which has no offensive connotations to them.
The hearer upon hearing the word reacts, consciously or unconsciously actively taking offence. A person intending to offend another within a shared contextual understanding is not inevitably successful. The hearer may respond with amusement, disdain, pity, or any other emotive reaction instead of offence.
Therefore, in order for a word to be offensive, all three of these criteria have to be filled, if they aren't, the word isn't offensive.