You never can tell. My next door neighbors are really nice. Older Romanian couple, bought the house and fixed it up. Have several adult children who come and stay with them sometimes. Have grandkids, one of which is my daughter's age (8), they play together sometimes.
Today, my wife comes home from her morning walk, finds a bunch of black suburbans lined up on the street outside their house and in front of mine. Turns out, one of the adult children had been messaging an undercover Homeland Security agent wanting to have sex with her 8-year-old daughter. And sent the agent several images of child porn. They traced the IP to my neighbor's house.
I don't know if I've ever met this guy. They have several adult children and spouses that I have met and I can't keep them all straight. But it makes me sick thinking I may have let my daughter play over there sometimes. Never had a bad vibe, they have always seemed like decent people.
I did get the impression in speaking with them that they were directly involved in deposing (and possibly executing) Nicolae Ceaușescu, but that's a positive in my book.