What's the best product(s) to clean dirty grout on tile floor?

Goo gone grout cleaner. Very easy and fast. Use all the time.

Baking soda and vinegar and a stiff bristled brush. We made the mistake of a light grout in our kitchen, which is our main entry. That mix does will

There is also a product called Grout Refresh, that is essentially like repainting the grout if it gets so bad that you can't get it clean anymore.

I have light grout in my kitchen and four dogs that are in and out of the dog door all day. I use hot water and a tooth brush once in a while and that does the job.

I tried everything on my grout and could never get it all one color everywhere, so I ordered some Aquamix grout colorant in the color smoke. All the grout ended up the same color and it never looked dirty again. It took a while to do this but was well worth the time and patience.

I use Zep cleaner for a lot of my built up cleaning. Wal-Mart and Home Depot has this product.

I highly recommend a product called Oxi Clean Max Force. Easy to use and makes grout look like new. Do a test sample first. After that use an old toothbrush to scrub it into your grout. Let it set 15 to 20 minutes. Then wipe up with clean damp cloth. This product works great.