When is it OK for you to (legally) swindle a business?

Which is worse: not paying for a refill at the soda or buying currency with a rewards credit card? The refills seem harmless, but they will eventually drive up the cost for all of the other customers. As for the credit card, the owner gets his reward airline mileage, the credit card company gets its transaction fees, and the airline is paid for the mileage – everybody wins. Unfortunately, it's not always so simple.

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