If anything the people living in the area around the plant despise the thing. Apparently it makes a ridiculously loud sound when it goes off, which must be pretty frequently. Do a Google search and you'll find links to local news channel reports.

I think one of the articles said that there are at least 70 of these things in North America, most of which are placed in the middle of fields to protect crops from hail damage. From what I read they should work in theory, but you're right there's no evidence that they actually work, other than that the Nissan factory hasn't been hit once by hail since they installed it.

I imagine if I had $10 million in inventory sitting in an unprotected parking lot I'd be willing to throw a few hundred K around on snake oil too.

And nice SF reference.