I remember back in college when I was in the University of Maryland Chorale. We did a trip through Germany, Czechoslovakia, and Austria. We visited many churches and such along the way, and in most of them we asked carefully and were allowed to sing a couple of short pieces (Billings' "David's Lamentation" is the one I remember, but I think there was a second piece). We sang in many rare places: the orchestra stage at the Bayreuth Festspielhaus, the music room at Neuschwanstein, and of course most of these churches.
It was about a week before the end of the trip, on a Sunday morning, when we arrived at the Weiskirsche. Not surprisingly, there was a mass going on, so we crept into the back of the church, looked around very quietly, and crept back out. But not before we observed two things. First, there was an array of signs in the back (in several languages) asking the tourists to keep quite and not take pictures during services. Second, all of the touist around us (mostly German) were talking-- loudly. We were absolutely mortified, and when we got back on the bus Dr. Folstrom, the director, thanked us for being respectful and expressed his astonishment at the behavior of the others.
This was twenty years ago.