I love when I'm reading something and I realize that the author knows what they're talking about, especially when I can tell they do even though I've never experienced something myself. Like in one story where I could tell the author knew how kids talked, I was well aware of how kids talk too, but in another that was about life in a cabaret, the subtleties of how the characters talked or what they did were too natural for me to believe they hadn't at least done some research on how things work there on a day to day basis even though I have zero knowledge of the subject. It sounds cheesy and pretentious but I'd describe it as feeling kind of like a secret between you and the author.