Few sentences in the English language are more dreaded than this seemingly innocent offer: “Oh, I must show you the pictures from my vacation.” … But, of course, those very same shots can be extremely useful when researching your own trip. How big is that pool? What, exactly, does the room at that five-star hotel you’re thinking of booking look like? What’s the crowd like at the so-called hot restaurant? It’s good to have documented evidence from someone who has been there.