The good steward is key. I've had swarms land in my back yard. From where?, I'd love to know. But I've had at least one a year for the past 3 years. The swarm queens are unmarked, my queens are marked still in their respective hives.
As a beekeeper it's awsome to see but when there are neighborhood (and my own) kids that could have been playing in the yard it's a potential problem. With that in mind, I saw the swarm through the eyes of a nonbeekeeper and it definately got my attention. You do not want a neighbor seeing a swarm issuing and moving about. There are bee's everywhere and it sounds like a back-back leaf blower. It's something a neighbor will never forget and if they are neurotic you've potentially got big trouble on your hands.
As a beekeeper we never really want to lose bees but if it happens and you are there in the middle of it, just go with it.
Stretch your arms out and take it all in, lose yourself and thank God you are alive and able to experience such a thing.
I forget everything when I'm in the middle of a swarm. I lose myself amongst the bees and feel like a little kid at Christmas time.
Just make sure you keep an eye on the swarm and if they rest nearby have even more fun collecting them.
Yes, I'm weird for bees, aren't we all?