In the case of the Magic Eraser, here's the secret of how it works: the white pad is a piece of melamine plastic foam. Melamine (melmac) is a pretty hard plastic, and in use the foam breaks down into little tiny hard abrasive particles. The abrasice particles remove a thin layer of the offensive mark. when you scrub with it.
Nanana, I can't HEEAARR you, I can't HEEAARR you...
There will be no such science talk around here: understanding how the World works is forbidden knowledge, as it undermines a belief in magic, which undermines a belief in supernatural forces, which in turn undermines a belief in You Know Who... ;)