Really? Isn't it going to throw a lot of false positives when people try to spend them and the cashier thinks that the misspelling means it's counterfeit?
I've been a cashier, and trust me, we had more important things to do than examine bills with a magnifying glass looking for spelling errors. If a bill seemed suspicious at a quick glance, I swiped it with the counterfeit detector pen, and if it came out fine, I shrugged and put it in the register.