Offence by dialect reminds me of a local Manchester radio news report many years ago commenting on a visit by Sir Vivian Fuchs and pronouncing it as 'fucks' because to pronounce it correctly would offend the local listeners as you can't say 'fooks' on radio.
And 'facking' is estuary English rather than cockney.

Here's Steve Earle not offending Americans in the intro to a song - quite a good line actually