Been riding in Arlington BD?
I've put a sock in the complaining and just taken it as a fact of life. Now the ice on the W&OD this am, that was fun!
Worst area of my commute is in front of Starbucks on Fairfax for the same reason you stated. But to answer your question, shoe polish comes off paint easily unless it's there for a few days. Then it's a beast to get off. On glass, it comes off pretty well
Roger