Last night’s winner: Simple Green.
Simple Green (actually a diluted version) got the surface type gross off without major issues. SG works best when most of the hard mortar etc is first scraped off with a metal scraper, and only time will tell how SG will hold up to the tiles with paint on them. No one managed to get the extra deep crackle-cleaning bonus points. Losers include big hitters like CLR, Clorox bleach wipes, and some other wannabe ’tile cleaners’.