Building sites can be chaotic places. There is often huge time pressure placed on contractors and this leads to mistakes.
Contractors and sub-contractors tend to focus on what they need to get finished, and while they might be experts in their field if they are not careful it is easy to create serious damage to stone and tiled surfaces.
Grout, glue, paint, and gib can all be problematic if left to harden on the surface of a tile.
No matter what the contamination is Slique can remove to return the surface to it’s intended condition.
Paint tins and building materials placed directly onto tiles can cause damage 
Construction work is very hard on tiled surfaces if they’re not protected properly