Using only the highest quality installation
He understands that:
A tub should drain and hold water as desired, not leak through the ceiling below.
A shower should give you evenly balanced hot water, draining properly and spraying on you and not everywhere else.
A toilet should flush with ease and flow downward out of the bowl into the sewer, not vice versa.
A faucet should spray into the sink evenly, not as a trickle and not on you, and should drain without leaking all over the things in the cabinet below.