That's scarry. You might have spanked a child in public, you might have allowed a naked child to run out your front door, you might have a neighbor who doesn't like you and complained a couple of times about your kids playing too loud. Just about anything can bring 'them' into your home and it is something that I have fretted about a time or two.
On the other hand, we homeschool and have 'visiting teacher' in our house twice a month. She is wonderful and loves our kids. There are families out there that kill their kids and lock them in closets for years at a time and every other sick thing you can imagine. The bottom line is that the world sucks and without the Lord, it will never even begin to make sense.