Chris Clark has a perfect example of why asking customers (or people in general) for their opinions hardly ever produces immediately useful results (unless you're studying psychology and want to prove the following two sentences): People can't judge their own behaviour correctly and objectively. They don't know what they want, or even how they behave.
There are only two ways to flip a card: over the horizontal edge or over the vertical. Seems pretty simple, but a flip in the wrong direction will make Side B appear upside down, and there's no way around it but to optimize your printing for the most common flip style. All you need to know is which way that is.
Think about how you flip business cards, and what you would do to figure out how people in general flip business cards. Then read how Chris figured it out.
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