I don’t like rubbing dust and dirt into the paint, I wash my bikes like I wash my car. Every other week or so I spray down my bike with low pressure water, and clean it with a soft brush, with a bit of dishwashing soap. I have a couple of brushes, a bigger one for the frame tubes and such, and a smaller one for getting into the tighter spaces. The brushes are soft enough not to damage the paint, but firm enough to lift off the dust, mud, and dirt.