I don't really think Americans walk around thinking black cats have a witch inside them. A lot of people here just like an excuse to do disgusting things on Halloween/Devil's Day. It just happens that cats are symbolically linked to the holiday.

Halloween is actually a big deal in the U.S., as compared with my experience in NZ where it is barely discussed. I remember a lot of protests in NZ over Halloween because it was an "evil" holiday. So, I guess we all have our superstitions.