People might get offended if you say that Chinese opera is awful, but it really and truly is to anyone who is not Chinese. It is worse than rap, in my book, and rap and hip hop were intended to annoy anyone over 20.
I have been told that the reason that when they put Chinese opera on TV, they have to have the characters running down the screen, because when Chinese is sung, the tune wrecks the tones of the language and it becomes largely intelligible to most modern Chinese. And of course, it is in Mandarin, so speakers of Cantonese, Hakka and etc. could not understand it either.
I don't think anyone has actually ever staged an entire Klingon opera, but the pieces that were presented on Deep Space 9 were at least as bad as Chinese opera.