Depends on how hard the glaze is. I have not had it scratch my ceramic tile in the kitchen.

I tried using sandpaper on glazed tile and it did not scratch it. Tile is very tough; ME are very gentle. I use them on painted walls to remove scuffs. Yes, a little paint comes off, but not all of it.

I was curious a while ago and looked up what the ME is made of. It is basically the same material as Melmac ( melamine ) dishes were made of. If you put it under a microscope, it looks like coral. It is the equivalent of a light sanding. For example, it will take the shine off of Formica. Did you ever notice that if you squeeze a ME it flattens? That is because you broke the melamine strands.

I've gone crazy with ME and have taken the shine off of countertops and stripped paint off of walls. I wasn't intending to do either but wasn't paying attention and put a little too much elbow grease in the job. I've learned that its a nice cleaning tool BUT be gentle and test it on a small inconspicuous area first.