Once again, I"m stuck in a book where the author thinks I care how much research she did. It's a mystery, but we keep stopping to reflect on the history of certain famous buildings, the eccentricities of certain famous people, and the operating processes of certain organizations. Any one of those things might be interesting except for two things. First, they have nothing to do with the story, and second, they're so obviously pasted on that it's like being hit in the face with a wet newspaper.
What's the difference between an author who can and an author who can't? In Nevada Barr's Anna Pigeon stories, I've learned all sorts of interesting facts about the park service and specific national parks, and never once have I felt that I was being lectured to. Bev Myers expertly re-creates the world of Venetian opera by alluding to costumes, objects, and behaviors that give the flavor of the time. Yet this author (and I'm on my second try with her) can't stop teaching the reader, even when she throws facts into conversation in what she obviously thinks is a casual manner: "Well, Hermoine, you're probably aware that the ** Society was made up of twelve members who came from many walks of life and attempted to represent the ideal...blah, blah, blah."
I love learning things in books, and I expect that authors will do their research and write from an informed viewpoint. What I don't need is all your research pumped into the seams of the plot to elongate the book and make you look really smart. Because it doesn't.