How to clean bathroom tiles... any advice?

[BabyGiraffes]

We've just had our bathroom walls tiled and only when it was done noticed that about half of the lovely large off white tiles have small dark/grey raised marks on them near the edges. Possibly a manufacturing fault or while they were stacked in boxes. DH is super stressed about this and drives me insane with talk of having them all ripped out again and replaced at huge cost - while I am just pleased to have a working bathroom at last at 38+3 pregnant with a lively toddler to look after... The usual tile cleaner/soap and water/ scrubbing has had no effect. Has anyone any experience with this or a secret recipe to try to restore sanity in our house?

Is it excess grout, perhaps some grout cleaner?

Try Brillo pads[grill]

Hi, orienteerer we thought it was grout at first but I had the idea to check the box of spare tiles, and they, too have the mark. We did phone the tile shop and they suggested tile cleaner at first, thinking it's some wax residue they put on tiles when they get stacked in boxes. This hasn't shifted it though...
Would a Brillo pad scratch the tiles themselves (matt finish)? May try on one of the spare ones...

Step away from the Brillo pads! Surely not serious Go for Cif cream cleaner on a soft cloth. Should do the trick - if not perhaps try Brasso or Bar Keepers Friend.