There are a few kids in our estate, most of whom come from the kind of families that we're happy for DD (8) to mix with and go to their houses to play.
However there's one kid, let's call him Tom, whose father is a known drug dealer. We're fine with DD playing outside on the green with the kid, but we don't allow her to go to his house.
She's getting cross about not being allowed to go to Tom's house - asking why not, what difference does it make, she's allowed to go to Jack's house so why not Tom's, and so on.
We're obviously not going to get into the real reason, so what do we say instead?