Chris: nothing fancy, just a liberal smearing of white shoe cream while I was cleaning the rest. It helped, but they will never again be box fresh.

Hmm ... good to know!

Mr. Clean white sponges (can’t recall exact name) clean off marks on plastic. I’ve been tempted to use on whir soles, but haven’t, lazy I guess

I’ve used nail polish and even Liquid Paper that I had around to touch things up! Rose gold nail polish helped me extend the life of some beloved ‘snakeskin’ leather Converse and the Liquid Paper to cover some dings on a bathroom vanity. If I had just a small mark to cover on a shoe I would try one of those. It likely won’t colour match perfectly but much less obvious from eye level than a black mark…

Try the Mr. Clean Magic eraser. It's the only thing that works on my Stutterheim raincoat. Depending in how porous the sole is, it should work like a charm without any chemicals. I just used water. And I'd tried everything on that coat because it has white panels that were filthy!

Yes - this is indeed annoying when wearing white sneakers! I spray waterproofing spray on my white-soled fashion sneakers (Puma Carinas) - and that makes it so that I usually only need to briefly wipe the soles (or rather, the sides of the soles -- I don't bother with the bottom) with a damp rag after each wearing -- it takes just a few seconds; the dirt comes right off. I do a deeper cleaning with a toothbrush after several wears -- but nothing intensive.