As the proud father of a brand new (well, three week old) sprog, I was
rather intrigued by this thread - I'd never heard of it before (and we
have a four year old too).

So, I asked my BYJW, and she says (rough translation) "Yes, but they
don't visit everyone - only the people who might be dodgy."

Well...there are hundreds of things I could say about that - in
relation to fjlij gaigin - but I'll just say: What do you make of
that, then?