We looked at a house one time with deadbolts on all the bedroom doors, maybe it was a similar situation to your ole buddy's with scary stepkids, the realtor wouldn't tell us.
If it weren't for my wife's mom, I'd tell gunflint the same thing as edwarderc2 about his folks. Sometimes it just will never work out.
To make a long stroy short, her folks were divorced, the mom got two kids, the dad got one (my wife) and the the mom blamed it all on my wife. When we were going to get married I talked her into going and seeing her mom, whom she hadn't seen in 8 years.
This is the way it went down:
Ring the doorbell
Ring the doorbell
Door opens
wife:"Hi mom, this is my fiance, we're getting married"
mom:"I suppose you're telling me that now just because you want a f*(ing wedding present"
We turn and walk away
me:"You were right, sorry."