Why Spring makes me sick #11

From the Spring Framework Reference Documentation: "the Spring IoC container allows a BeanFactoryPostProcessor to read the configuration metadata and potentially change it before the container instantiates any beans other than BeanFactoryPostProcessors."

Sounds harmless, but is the worst I've found so far: Using BeanFactoryPostProcessor one can change any property of any bean.
The concrete BeanFactoryPostProcessor implementation does not have to refer to the beans it modifies and can be added to the config with a single XML element, that does not refer to BeanFactoryPostProcessor. In other words, one can really fuck up any application with under 10 lines of Java & XML, in a way that is very hard to detect.