What do vampires do? Not to paint with too wide a brush, but vampires tend to run in monster mode most of the time. Scuttlebutt has it that there are movies and books targeted at wide-eyed teenage girls that portray vampires in a sympathetic light, but it's doubtful that parents anywhere would allow their daughters to date a vampire, especially not one who sparkles.
And what do federal enforcement authorities do? Well, they enforce. They are always in enforcement mode. To invite them in to your place of business may open you up to all sorts of liability. It is generally not the smart thing to do.
Now don't misunderstand. This is not to suggest that anyone should obstruct or impede federal authorities from doing their job. You should never do that. However, you may want to avoid doing their job for them.
Beware enforcement officials bearing gifts. The government talks trade facilitation, but acts enforcement. If a cop were to drop by your home and asked you to come in. You'd ask why, and the cop would say, "we're doing community outreach and we just want to tell you what is legal or not legal. While we're here, you wouldn't mind if we looked through your computer, would you?"
You laugh, but US Customs and Border Protection (CBP) uses a similar approach in Significant Importer Reviews, a cryptic program of suspect provenance and design. CBP claims that Significant Importer Reviews are informal, friendly outreach visits that allow importers of a certain size and volume and CBP to know each other without risk to either. The problem is that these outreach efforts can easily devolve into fishing expeditions. The other problem is that there are no formal guidelines or regulations regarding this program to restrain CBP from overreaching. Indeed, CBP has not reduced any of the program goals or guidelines to writing, a red flag to importers if there ever was one.
Outreach efforts from enforcement authorities can harm exporters as well as importers, of course. Take, for example, Powerline Components Industries, a company that is currently featured by the U.S. Bureau of Industry and Security on its website (which is not a good thing). Powerline shipped diesel engines to Syria without the requisite license. The question for export enforcement authorities was whether the violation was intentional because if it was, then the penalty could be stiffer. Just about the time it was about to ship, enforcement officers paid a friendly outreach visit to the exporter during which the officers described the nightmares that befall violators of US sanctions laws. With that warning, Powerline knew or should have known that the export was illegal, i.e., it had the requisite intent. Enforcement authorities had little trouble forcing the company to pay a hefty penalty.
A vampire could not have done better.