I saw something similar done in a bathroom last year. Was called to do a consult on wether the whole thing had to come down or not. Aparantly two poles had done it, and they thought they had done a real good job, and were proud of it... They were present when I visited the place.
They had used like 12mm trowels on the walls, and managed to get like 40% coverage on 20x20cm tiles. On the tiles closest to where the doorframe was supposed to be, I could stick a pen in under the tile, like, all the way.
I almost felt sorry for them when I told them that their work was seriously botched, and that everything had to come down, as well as the floor, because they had damaged the UFH. There was a water leak as well, which they likely caused when they nailed a guide to the wall, using 5" nails... The list goes on...
Edit: And the leak had damaged the ceiling in the apartment below...