keeping my Danskos white!

Okay....I splurged on the Professionals and absolutely love them! My feet, legs, and back are OH so happy now.

But....I have a few scuff marks on them and it makes me sad. The salesperson told me you should only use a damp cloth to clean them, as anything else will ruin the finish. The website says soap and water, with polish as needed for scuff marks. Someone at work mentioned shaving cream? Now I'm not sure what to do. I bought white so they could do double duty for school. Plus I think white shoes look really nice - as long as you keep them white!

So give me your secrets: what do you use to keep your Danskos (or any leather shoe with similar finish) white, without discoloring them?