I've received checks with watermarks, temp-sensitive ink, you name it, and I almost never walk into a branch anymore. As long as the mobile app works, the image is the negotiable instrument, and I can't change what others give me.
It seems that a third-party check printing service could run off checks for the attacker instead. The attacker would need to cover their tracks insofar as payment methods, and then intercept a package which would be mailed to my home address listed on the checks they ordered. That seems elaborate, but doable, if they want a whole stack of legitimate checks.
It is possible that there are even disreputable "security check" printers who aren't Walmart, but just counterfeiters in a 1BR, running off bogus checks for anyone who asks?
But who needs/wants a whole stack of them, anyway? It only takes one or two.
It is so strange, too, that we rarely hear of check fraud in the States. It would seem so easy, so is it widespread or rare?