OK...
Example A: Steven Hawking proposes a new Grand Unified Theory. An astronomer, using the Hubble, makes some observations that shed doubt on a couple of assumptions basic to Hawking's theory. He publishes a paper laying out these observations and their implications for the Hawking GUT. I think we would all agree that this is scientific activity.
Example B: Scientists use a theory of evolution that assumes random natural selection processes. One scientist examines recent discoveries in the field of molecular biology and discovers observations that shed doubt on the assumption of random natural selection. He publishes papers (and a popular book) laying out these discoveries and their implications for the evolutionary theory.
Why exactly is it that Example A science and Example B is hoodoo?