QR codes are everywhere now and they have built-in error correction, which is a fancy way of saying they come with backup data. A scanner can still read the code even if about 30% of it is damaged, smudged or covered up. Now the scary part: Scammers love QR codes. They paste fake QR stickers over real ones on parking meters and signs. Before you scan, make sure it’s not some sticker slapped on. After you scan, read the web address before you tap or pay.