Kevbos. I am a customer focused tiler. I like to provide a tiling job that the customer wants. However, if I know something is technically wrong with a high risk of failure, I walk away. It is too expensive to get caught out with a large failed tiling job. I have been called to assess five cracked tiled floors in the last 18 months. In every case the floor was "professionally tiled". In three cases the tiler clearly ignored the likelihood of tile cracking due to the sub strata (usually by not using uncoupling membrane). In each case the original tiler refused to talk to the customer or take responsibility for their own work that had failed. Sometimes I despair of this trade.