I read an interview with the manager of an L.A. comedy club who'd known him for decades (sorry I can't provide a link) -- she said that, while she was widely thought to have known him well, she never really knew him; he was always full of voices and characters, but that he always seemed to be in pain underneath it all. Tears of a clown, as Smokey once sang.
I also saw this posted on my Facebook feed, and loved it. (Volume is low -- you will need to turn it up.)
http://youtu.be/Vz-K74MG6RU