I dont know which of the pieces it was, but I do know that the Horn concertos were written in bits and pieces, and that they were made for his friend to play. There were quite a lot of comments written in the margins, and I think that Mozart used quite a lot of scatalogical notes , so possibly that might be the reason it was seen as "infamous". There are many wonderful pieces of Mozart, and normally I hate the way that adverts take and misuse good music for their own purpose. But there is one Mozart horn concerto I can never hear without my brain adding the words, that the wonderful Flanders and Swann , made so popular. I can enjoy it from an orchestra, or with the f and s version. To see the young man tonight playing one of the horn concertos with his foot, as he was born without arms. It was very good amd you see how well he was able to use his foot.