Harry Shearer is among them.
http://en.wikipedia.org/wiki/The_Day_the_Clown_CriedAlthough never seen publicly, the film became a source of legend almost immediately after its production.
In May 1992, an article in Spy magazine quotes comedian and actor Harry Shearer, who saw a rough cut of the film in 1979:
“ With most of these kinds of things, you find that the anticipation, or the concept, is better than the thing itself. But seeing this film was really awe-inspiring, in that you are rarely in the presence of a perfect object. This was a perfect object. This movie is so drastically wrong, its pathos and its comedy are so wildly misplaced, that you could not, in your fantasy of what it might be like, improve on what it really is. "Oh My God!" — that's all you can say. ”
Shearer also goes on to point out why Lewis would make the film: he believed "the Academy can't ignore this." Upon seeing the rough cut, he told Lewis the film was "terrible", which reportedly made him furious. When asked to sum up the experience of the film overall, he responded by saying that the closest he could come was like
"if you flew down to Tijuana and suddenly saw a painting on black velvet of Auschwitz. You'd just think 'My God, wait a minute! It's not funny, and it's not good, and somebody's trying too hard in the wrong direction to convey this strongly-held feeling."