Do tell. Our company and most similar companies have a mandatory drug screening prior to hire. We've hired felons in the past but have no longer done so because of the market for qualified labor. I suppose there are a lot more shady characters that end up in residential services and trades because of the lower standards of those companies.
I always assume that any stranger in my house is a potential threat, regardless of whether they are packing or not. If I didn't like the vibe I got from them I wouldn't let them in, again regardless of whether they were packing or not. I don't assume the presence of a firearm is an indication of nefarious intent nor do I presume that a tradesman has just as much integrity and the same moral values as I.