Atrocious, ineffective endings to major works or movements aren't as rare as you might believe. Here are three especially egregious efforts by composers who should have known better--who are in fact so famous that we delude ourselves into believing that these awful endings aren't really so bad after all. I challenge you to listen afresh and decide if you choose to accept received opinion.
Musical Examples courtesy of Naxos Records, Brilliant Classics, Hänssler Classics, and Supraphon Records