How do I bathroom / kitchen / extension? etc.

Thanks.
It's because I would dread the idea of getting those tiles out and find out what's lurking behind and then trying to make something nice.
I have bathroom and kitchen done by someone with what seems the same level of competence and care as @bobble, everything I do makes me want to smash it all out as stuff makes no sense.
Just new silicone was a nightmare because the gaps/corners all looked like that corner on the picture. Hanging a new basin, new kitchen worktops, everything is annoying.