I was at the Baseler Karneval - "Morge Streik" (I think) about twenty years ago. It is quite a unique cultural event. Unlike most Carnival areas in the German speaking world, it is not a predominantly Catholic tradition. It also takes place a week after all the others. Apart from the pipe and drum bands and the candle illuminated masks and lanterns, which give it a strange, eerie aspect - quite unlike the bombast of Carnival elsewhere - there is the tradition of Gugga Musik. A brass band will appear in a pub and play three songs. At least one of the instruments will be slightly out of tune. This is apparently quite deliberate.
I recently heard a glockenspiel (not unusual in German speaking countries) and grimaced as I always do at the (to my ears) out of tune chimes. Indeed, I do not think I have ever heard one that sounded in tune. Are glockenspiel supposed to be out of tune too? It set me thinking about the question of what types of music are expected to deliberately differ from standard intonation?