I could never manage the dialect living in Bavaria -- locals regularly asked me why I spoke to them only in hochdeutsch, and I was even accused of being a SauPreuss.... and then I explained I was an American. I actually had to show a couple of people my passport before I convinced them I was not German.
Bravo, Cato. Sie waren sicher sehr fleissend! I too was complimented a lot for my having learned the language so well. I guess I am a natural mimic or something. I still speak Hochdeutch with an obvious Swiss accent.