Remember, the 'customer' is always right. [=never argue with a customer]
He is one tough/tricky 'customer'. [=he is a tough/tricky person]
The company has good/poor 'customer' service.
(..) You run all over town, don't you? Travis? - You run all over town, don't you? - Yeah. I mean, you handled some pretty rough customers. Yeah, I have. - You carry a piece? - No. - You need one? - No. (..)1976 Taxi Driver