FUCKING & FOREIGNERS

I have been a lexicographer for over twenty years so I know  everything there is to know about compiling the entry 'fuck' for a bilingual or monolingual dictionary. From the smallest pocket dictionary to the largest several-volume tome, I have had to analyse 'fuck'. Had she not been cremated, my old granny would be spinning in her grave at the thought of her granddaughter being paid to discuss the nuances of 'fuck' in meetings, given she told me once she would never let that disgraceful word cross her lips!
Something interesting has been starting to strike me about 'fuck' and foreigners over the past two or three years. There seems to me to be an inverse correlation between how good a foreigner is at English and how bad they are at getting the nuances and the register of 'fuck'. As foreigners become more competent in English, they believe they can use 'fuck' and all its lemma, whereas those who are less fluent actually believe me when I put three warning stars at the word in a dictionary I am compiling.
Often I notice when I am on Facebook that foreigners who are excellent at English - in particular Scandinavians, Dutch and the likes use it in their facebook status - things like 

• 'Nursery closed today - fuck!'
• 'Foggy weather today, fuck!'

I, as an English native, know fuck is way too strong for these comments, but the foreigners seem to think 'fuck' is on a par with 'shit', which it most definitely isn't. Too many American movies have somehow led the non-native, fluent English speaker to believe 'fuck' is something every grandmother utters when the rain comes on while she's hanging out the washing!
This week, I have come across two other examples of 'fuck' in a very non-native context.
Firstly, I was wandering around a large toy shop in Arezzo when I was stunned to hear the music piped in the background was Lily Allen's 'Fuck You'! A catchy, cheery wee tune but believe me - you are never going to hear it piped into Toys R Us in the UK! And later the same day I was passed in the street by a couple, who looked not unlike Thomas and I in age and type, walking up the main street in Arezzo holding the hand of a child - a little boy of about 6, 7 at most, wearing a simple black T-shirt, plain except for the slogan 'Fuck off!' in large white letters. You just wouldn't see that in a native English country.
I'm not a prude, I am happy to use the word in its correct context but I really am considering writing a course for foreigners to get them to understand it in all its glory.