To qualify as a useful swearword, a word must have one of more of the following qualities:
- Transgression. It must be a taboo word that is generally regarded as unacceptable, either because it refers to a sexual organ, a sexual act, a taboo person, a deity whose name must not be taken in vain.
- Plosiveness. It should contain the consonants "sh", "k", "t" or the vowel sound, "uh", or (even better) a combination of these. (These are the relevant phonemes for English - other languages may vary.)
- Brevity. It must be short.
The more a swearword is used, the less transgressive value it has, because it becomes part of the user's normal vocabulary, and its transgressive quality is lessened by over-familiarity (my dad came up with this aspect of the theory).
Sometimes you really need to swear because you have dropped a brick on your foot, or discovered that your bank-account is empty in the middle of the month. So you might as well save those really satisfyingly transgressive swearwords for when you really need them. Using swearwords as a hyphen isn't really very cool. (Unless you're Ian Martin, in which case it's absolutely fucking hilarious.)
Ethics of swearing
If a word ought not to be taboo because the thing, person or act referred to is not shameful or disgusting (e.g. witch, "bugger", cunt, prick), then it should not be used as a swearword. Unless it has become so current that the original meaning of the word has been forgotten (e.g. "bugger", "bloody"). Again, this rule does not apply to Ian Martin, who has taken swearing to a high and magnificent art-form.
If the person referred to does not exist, how can they be offended by their name being taken in vain? (Nevertheless, it does seem odd for atheists to say "goddamn" or similar. Maybe they could say "Dawkins!" instead - it has a great plosive quality...)
That pretty much leaves only scatological swearwords.
However, the Latin names of fungi have great possibilities as swearwords. How about "Hidnum repandum!"
Swearing in a foreign language is also rather satisfying, e.g. "Arschloch!"