If you're still in the neighbourhood on the second weekend in October, and you want to try a real local festival, I heartily recommend a trip to Hellring just south of Regensburg (about an hour north of Munich.) Four local families host the festivities (based on a religious pilgrimage), with wonderful home-cooked food (Schweinebraten, Knoedel, Weisswurst etc, etc -- diet, what diet?)
And, need I add, fantastic beer. Kelheim is just a few kms down the road, so the Schneider Weisse is 100% fresh, as well as beer from several other local breweries, all of it unbelievably great.
You will be unlikely to find obnoxious, drunken Aussies, Poms, Kiwis, Yanks, South Africans etc...only drunk and friendly locals.
www.hellring.de
(Only in German.)
(Edited for date stuff-up...although you could still turn up any time in that neck of the woods and have a ball.)