I'm with Thomas in this matter. I don't care about the few stains my top has; they're character in my eyes and shows frequent use, which is what a working saw should reveal.
I'm more interested in how well the stock moves over its surface. To that end, I simply apply a coat of Johnson's Wax when necessary.
If I'm cleaning or removing a bit of surface rust I go with WD-40 and a gray Scotch-Brite pad and then apply the wax. The WD-40 rids the surface of moisture while the solvent and the pad loosen and remove grim and light rust. I never shoot for a like-new look because it won't stay that way around here!