How about this? You realize that their pathetic lives couldn't possible contain even the briefest moments of happiness, no matter what happens to them.

I know you can't actually say this to a customer, but it may help to think it;

A. "Madam, it's abundantly evident that you've had a tragically unhappy childhood, but it won't help you a bit to try to take it out on me".

B. "The other customers say you were toilet trained with a cattle prod; is that really true?"

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