Someone hands you a business card, and you put it in your wallet. It’s a couple days later, and you need to get a hold of this person. You reach into your pocket, pull out the business card, and wonder why you need a magnifying glass to see the type.
Keeping your fonts above 9pt are very important. When proofing it, just by looking at your print job on screen is not always good enough. There are several reasons for this, but size is most definitely one of them.
I have a customer that wanted to make the font size on his business card smaller. I highly recommended we do not do this, because anyone with bad eyes would have a hard time reading it. My biggest suggestion is to either see a proof, or to print it to scale on your own printer so you know how it will look! It may look great on your screen at 150%, but it is important to know how it will look on paper at the actual size!
What is the weirdest or most difficult business card you have seen to read?