Cunt is, when said correctly, the worst word in the English language beyond Oxford I think.
I try not to use it in speech, although fuck trips off the tongue far too easily at times. It's always good to have such words, they are reserved for when you really need to make a point and the more they are used the less effective they become.
Strangely some people also have the same feeling for Twat, which I always used to use freely like bloody hell, thinking it was quite a harmless slang word.
you sounded like a cunt on the radio this morning
only joking rob you got your point across very well