This is one of my best sets of before and afters for a tile and grout cleaning, colorseal job that I have done. The tile itself was not very dirty do to this particular tiles non-porous nature, but the grout was very soiled, and being a white grout showed the dirt quite well.
I do not have the picture of the grout after I cleaned it, but the picture below is after the grout was sealed with a white colorseal. The grout after cleaning was still a little dull looking and not 100% consistent, a little blotchy (a little redundant)
This grout cleaning/sealing job is a great example of why I love and encourage colorseal to my clients. It gives the grout a great look while giving it an excellent seal that is much easier to clean and maintain than impregnating grout sealers. This is tile on a master bathroom floor so it will not face the oils and stains possible in say a kitchen where there is grease and sometimes wine potentially being spilled, but if it was the colorseal will hold up very well there as well.