I was very annoyed when I realized the plumber installed the water cut-off valves for a new stacked washer and dryer that would end up physically behind the unit. The water cut-off was physically directly above the the drain pan and all the way in to a corner. You would need to be at least 9 feet tall to lean the washer/dryer forward and then shut the water off (or you need two people). I didn't think of that until the installer dropped the unit in place and no one could reach the water.

Did they come fix it - yes-ish. If I had had them move the water they would have charged more so we just moved the drain pan (aka physically where the washer/dryer sat. As a result now you can see a plastic pipe (for the drain pan) on the floor.

He also forgot to glue all the sections of pipe (for the drain pan) together. Annoying....

Lastly, I have just learned that they should have pulled permits for the natural gas pipe work. They did not ever bring up the need for permits. Some people may consider that a plus.