Creator Backlash: Walt disliked the final product of Alice in Wonderland, and was happy that it failed at the box office. Considering how big a fan he was of the Alice stories (the Alice comedies in his early career to the Mickey short 'Thru the mirror'), he felt that the movie didn't do it justice. And for a brief time, he grew to hate Snow White because of how it overshadowed his later features, despite making them as attempts to build upon and improve on what Snow White established. Fortunately, he warmed back up to it in his later years.
Doing It for the Art: Walt took this very seriously, and even had this quote for it. "I don't make movies to make money... I make money to make movies." That said, he still had enough common sense to be careful about how he used his money, especially after the early 1940's.
Old Shame: He hated his last directorial effort, "The Golden Touch" (1935), so much that he never directed another cartoon again after that. The story goes that he took over directing duties to show his regular directors "how it is done". The final result was considered disappointing, and Walt felt the failure to be humiliating. Curiously the "Touch" is actually among the best remembered Silly Symphonies due to certain Black Comedy elements.
What Could Have Been: Walt had a whole bunch of projects planned out as animated films that didn't get made. Concept artwork of these proposed projects can be seen in the book "The Disney That Never Was".