A few years ago the mother of an ex-girlfriend came to visit. She said to us "you know, I think I'm starting to understand Swiss German, it's not that difficult". We had to politely inform her that the interactions she had had up to that point had been with Swiss speaking "high" German for her benefit, and not Swiss German at all .

Just a tip (for those who are perplexed) - don't be afraid to ask someone to speak high German, I do this all the time. Most educated and polite people will automatically answer you in high german as soon as they notice that you are a foreigner or if you answer them in high German. There are always those who will continue in Swiss german but if this is the case I usually politely ask them if they could speak with me in Swiss German. Usually at this point they will immediately apologise for failing to recognise the fact and switch. Only on a handful of occassions have I encountered people (adults) who were either unwilling or unable to switch to high german, and to be honest I don't think it was really worthwhile speaking with these people anyway