Which only works until you call in asking for a password reset and when they ask you the question you just say "I just hit the keyboard a bunch".
Anecdotally, I had a time where I couldn't remember may answer to a secret question except that it was a type of food. I called in and the human on the other end let me reset my password with just that explanation. Take that for what you will, but it seems like if someone knows you use passwords that are random strings, they can use that to break in.