That sounds reasonable to me, it does seem darker in the British usage. Also - in US English, you could call someone an "ass" - its not really that bad an insu

That sounds reasonable to me, it does seem darker in the British usage. Also - in US English, you could call someone an "ass" - its not really that bad an insult, like you said, more about their behaviour at a point in time. There is also the donkey meaning (ass) which makes it less insulting then it would otherwise be.