were they sealed prior to grouting? I think they need to be.

My floor tiles had the same, but were porcelain... just saying you might be right: any grooves or pits hold the grout after the 'swiping/ cleaning' part...?

I had to accept it too. :)

that's why I wondered if you had sealed them prior to grouting. They probably absorbed the grout.

That may be the nature of cement tiles. Cement tiles are not glazed and smooth like porcelain or ceramic tiles. Do you have extra unused, unsealed tiles you could compare them to? I too have cement tiles, although they are on the floor, and if I look closely, mine also have tiny pits and the color is more intense in some areas than in others.

Five minutes later, I wanted to post again, because I remembered that you can have cement tiles polished and resealed - and perhaps they should have been buffed and polished before sealing...or maybe you did do that. So, you may be able to buff them and reseal them if you are unhappy with their appearance. I do not know what kind of medium is used to buff/polish them, but whoever manufactures the tiles should be able to help you. This is usually done professionally.

I don't know what they're supposed to look like, but I'm willing to say that they look great the way they are!