Double Negative

I was told nothing is different in the dark than in the light
  But it is
I was told a baseball bat is something to play with
  But it isn't

I was told if a dog is waging his tail he is friendly
  But he wasn't
I was told a relative is safe and would care for you
  But he couldn't

I was told parents are kind to their children
  But they're not
I was told guns can be safe and protect you
  But they don't

I was told there are no real monsters
  But there are
I was told you would know who they are
  But you won't