IMO there are no profane words. There are words that might be used in a profane manner. To explain; at the age of 30, while walking in a city park where they also had an on-going dog show, I heard over the loud speakers, "The showing of the bitches will be at two o'clock." I actually cringed & ducked but it made me think about words. Early in this thread a posted mentioned that in years past we would never say a woman was pregnant but would use some other wording to essentially convey the same information. Was the word "pregnant" profane? Was the fact that she was pregnant & in public profane? Since it was OK to discuss it (using other words), the state of being pregnant & in public wasn't what was profane.
Another incident in my life was trying to explain profanity to my (then) 12 year old daughter. I used as an example the term "BS" & said in today's society, most people would find that somewhat acceptable but if we said "Bull s...", many people would frown on us. On the other hand if we said "male bovine feces", those same frowns would likely become grins. In the final analysis, we had just said the same thing in three different ways analogous to saying "in the family way" instead of pregnant.
So my conclusion is that the profanity is not in the word or even the meaning of the word but in the social circumstances where the word is used. Just as different words have different meanings, the same word used in different social circumstances has a different connotation. Our society, as a whole, determines which words are permitted in each social circumstance.
I've found that we typically frown more on the short, concise way of saying something, hence the reference to four letter words. (BTW other four letter words are love, mama, this & that
) Perhaps it's because the longer, more stilted way of speaking allows use to approach an idea more slowly.
As a final note, my wife says that "bitch" is not necessarily a derogatory term. I'll leave it to your imagination what she might mean by that.