I honestly think our swearing hierarchy is flattening out. Gill's right that the truly unsayable (in polite company) swearwords are all racial. An awful lot of other words depend entirely on context and voice to get their force. 'Bastard' for example can go from 0 to 100 on the insult scale depending on whether it's accompanied by a smile.

I remember my mum being very annoyed that 'fuck' had passed into common usage, because it reduced the 'proper' swearing possibilities. And she's a nice middle class middle aged lady.

I wouldn't say 'cunt' at work (or at all, for preference), but I've certainly said 'fuck' in the office without problems. It's possibly my mum had a point.