How to Remove stains on painted walls inside house?

For stains on walls I usually use Mr. Clean Magic Eraser. It isn't harsh or abrasive and really cleans off just about anything (including sharpie marker).

DO NOTS: Bleach can change the color of the wall and in some cases strip the paint. Brillo Pads are just too abrasive and can strip paint. 409, Orange Clean, Windex, and Simple Green or just not strong enough to clean off stains or can have a reaction with the wall paint.