As I mentioned in the mini-ep thread, I interviewed director George Romero a few years ago for a blog. He didn't seem overly impressed with his own work on Monkey Shines:
Q: Are audiences tougher to scare these days?
A: I haven’t tried to scare anybody since (Night of the Living Dead). To me, since then, all my films have been like comic books. I haven’t tried to get under your skin at all...
Q: That’s interesting. I remember being particularly scared by a film of yours, when I was young, called Monkey Shines.
A: Monkey Shines? How young were you?
Q: About eight years old.
A: OK, that might do it then. I guess it had a few scares in it. If you’re at an age where the concept is frightening to you, it works on that level. With that film, I thought it was more a Jeckyll and Hyde story. Maybe I’m too jaded.