So I had heard about a cleaning tool called a "grout pen" from my dad however when I asked the folks at Home Depot (figuring that was the logical place to go for something like this) they looked at me like I had made up this amazing invention. Turns out I didn't need to go to Home Depot but my local neighborhood Target now that Tilex makes a Tile and Grout Pen. If you have tile you need to buy this pen. I live in an old building and the grout in my kitchen is probably from the 50's. I used this pen on it and it is WHITE again. It wasn't as white as I would have liked when I initially wiped it off but it kept getting whiter as the bleach finished soaking in. I do recommend that you put on an old shirt to do this as while I was extremely careful I still got a tiny bit on the shirt I was wearing. Bleach + black = bad news.