it can be a good idea but has a big problem, and that is the issue of trusting you.
since you are the one creating the paper wallets and the private keys, the buyer needs to trust you are don't have the the private keys so the paper wallet won't go empty after the purchase.
True, but I am in the USA. Plus if I did what you are saying, and I'm taking payments by credit cards, there is no doubt that I would get arrested within a week.