Four things break printed QR codes: printing them too small for the viewing distance, low contrast, no quiet zone, and cramming in too much data. Check yours before it goes to print.
Corner of a card, read up close.
Café or restaurant table, arm's length.
Storefront window, from the footpath.
Wall or noticeboard, across a room.
Six things worth checking before a printed QR code goes out the door.
SVG or PDF scales to any print size without going blurry.
Light-on-dark can work, but needs a higher contrast ratio to be safe.
Don't crop or cover the blank margin — cameras use it to find the code.
Especially if a logo sits in the middle — it needs the redundancy.
Glossy laminate creates glare that confuses some camera autofocus.
An older, cheaper camera in bad light is the real bar to clear.
A code that scans perfectly but lands on a page you have since moved. That's what the rest of Linqt is for.