This is more complicated than just blacklisting e.g. "gun", because that will miss things like "O.F. Mossberg & Sons", which is a firearm manufacturer. While a lame blacklist will likely do the trick as far as passing due-diligence requirements, I'm interested in what the "right" solution looks like.
TL;DR — is there a service or library that matches input data against sketchy/regulated/illegal/risky businesses?
[0] https://stripe.com/blog/why-some-businesses-arent-allowed