Wuyi, the funky flavor is probably not related to brown sugar. Most European ciders have this barnyard taste to one degree or another. It is known as "old horse" in the UK. You would have a hard time finding a bottle of cider in France or Spain that doesn't have some variation on this. People either love it or hate it. They most common cause is wild Brettanomyces yeast. It usually takes a while before it develops and most people who are posting to this forum seem to bottle and probably drink their cider long before that taste develops. Once your equipment has been in contact with Brett, it can be hard to get away from it in the future so if you hate it, you might have to make some serious efforts to disinfect all of your equipment or throw them away and start with new, clean equipment.