Too lazy to look it up, but there was a teevee preacher in the US who got indicted for mail fraud. He promised people that, if they sent him a "donation" along with their prayer request, he would pray to the Lord on their behalf. His secretary testified that she was in charge of opening envelopes, pulling out the cash and/or checks, and tossing the prayer requests in the trash. The post office didn't take a position on the efficacy of intercessory prayer, but the fact that the man promised a service which he didn't provide was a crime.Speaking of weird laws, the Vagrancy Act of 1966 made it illegal to pretend to tell fortunes, or practice witchcraft, sorcery or enchantment. And they kept that as law until 2005. (It's still illegal to engage in fraudulent activities while claiming to practice witchcraft or fortune-telling, of course. That comes under "fraud").
I'm using this in my novel; MC is very careful with how he phrases his scams.