I can understand Lisa Simpson although I don't necessarily agree with it. But he does make a good argument for her inclusion.
Slimer, Serpentor, Snarf... totally agree. Although I just never thought of it before.
Scrappy Doo, on the other hand... I have hated him since I was three years old. I never liked that arrogant piece of dogshit. He ruined Scooby Doo for me.