Interesting. Here in my bit of England, "bastard" would depend on intonation - said viciously it would suggest he's pretty much irredeemable, said with affection it would be OK, possibly sounding slightly Aussie. "Bugger" varies hugely from area to area - a Geordie uses it as a term of endearment, while in some parts of the Home Counties it would be taken as obscene. Ditto "sod". "Retard" is something I've heard twenty-somethings use, but I find it offensive and avoid it. "Dickhead" could just mean he's done something stupid or could be nastier.

Racist abuse is more or less beyond the pale, especially "Paki", "coon", "wog" and "nigger", though that last is not as unsayable as it is in the US. "Fuck" is often used as a form of punctuation, especially in rougher society, but "cunt" is absolutely beyond the pale except as a really vicious insult.

As for American English, I've had several amused guests enjoy faggots with mushy peas in a local pub. And in Britain, "One thing I don't like about fags - all the butts you see in the gutter." has a totally different meaning!