I've seen apps that read QR codes that don't, however. Usually they're single-purpose and just don't recognize unexpected data (scan the magic code to get a character in a game, etc) but if the expected data is formatted as a URL, maybe it tries to fetch resources there (character information and image).

I can also see someone making a browser extension that allows scanning a QR code to immediately open it so you don't have to leave your current app.