Because they break the third Commandment of Teh Ten Commandments of Ceiling Cat, which states: "Don' lissen to Basement Cat."
In order they go:
1. I iz Ceiling Cat
2. Ceiling cat comez 1st.
3. Don' lissen to Basement Cat.
4. Don' use mai name to do eveil things.
5. Remember Caturday n keepz it...