Clean Walls? Is there a simple and nippy way to verbs walls without drawing...

Is there a simple and nippy way to verbs walls without drawing them over or calling a contractor?
I have walls that go and get dirty easily and they are really filthy how can I draw from the stains off next to a quick remedy somehow?
Answers:    soap, river, and elbow grease.......maybe for a time bleach......if there is a stain
within is a product for paint prep called TSP. distribute it a try.