Okay, I've had my mind blown because I found out that it's apparently a thing to give out a spare key to your house. DH and I are the only ones with keys to our house, in the past when we've gone on vacation, we give my set of keys (which has an alarm fob on it to turn the alarm off so they don't get given the code to that, either) to whoever was coming to feed the cats while we're away. We get those back on our return, obviously and nobody has a key on a regular basis.
So, does anyone have a spare key to your house? If so, why did you choose to give it to them and for what purpose has it been used? Has anyone had someone misuse their spare key? Finally, are we really the only ones who are uptight enough to not want people to have unsupervised access to out house on a regular basis?