Glad you got back OK. It's always a question - whether to go armed or not. Quite honestly although I have a CWP, I only tend to go armed if I'm out at night. Filling stations are one of the most dangerous places to be at night although I'm more likely to hit an errant deer while driving and being a humane kinda guy, if it was lying in the road unable to get up I'd put it out of its misery.
As for abandoned factories, I'd want to scout them from a distance before approaching. Bearing in mind also that people high on LSD aren't going to realise they have been shot, it might be more appropriate to have several armed friends with you.
I love old, abandoned buildings. My chief concern here in SC is not bad guys - they're big enough to spot. My concern is more copperheads, cottonmouths, black widows and brown recluse etc.