I tried using a dark gray grout with my white subway tile to be different, and now the whole wall looks dirty from ten feet away. Anyone have a good grout cleaner they swear by for this exact problem?
That dark gray grout with white tile is a classic combo for a reason, it gives clean lines. The dirty look might be from haze or uneven application, not the color itself. A good acid-based grout cleaner from a tile supply store, not a big box, usually fixes that. You have to scrub it in and let it sit, then rinse really well.