In the current Nancy Drew Diaries series, Nancy is reluctant detective. Each book generally features her friends making jokes about how she's mystery-obsessed, or Nancy herself will complain about how she dislikes mysteries. Well, maybe she doesn't complain as much as she thinks something like, "Oh jeez! Please let this incident be an accident! I don't want this to turn into a mystery! I'm trying to take a break from mystery solving!". (Book 12) And so, 2-3 sabotage incidents have to occur, before Nancy will admit there's a mystery here that needs solving.
This is in contrast to the original series Nancy Drew, who was sometimes so obsessed with mysteries, you could say she actively sought out mysteries where there were none. "The doctor looked angry as he drove past me? That's a mystery!" (Book 10) That Nancy will sometimes complain, when there aren't mysteries to solve. Usually, that happens at the end of the book, and the author says something like "Nancy's wish for another adventure would be fulfilled sooner than she expected, with [THE NEXT BOOK IN THE SERIES IN ALL CAPS]!". I've seen it happen at the start of a book though, and the author will use it as a springboard to talk about an earlier book.
Which personality is better? Reluctant Nancy Drew or Overeager Nancy Drew? I'm more used to Overeager Nancy Drew, myself, but I prefer a Nancy who's more in the middle, as opposed to being one of these two extremes.
The Nancy Drew videogames tend to have a fair mixture of Nancy's attitudes towards mysteries. Sometimes, she gets summoned to a place to solve a mystery. Other times, she stumbles upon a mystery by accident. Although at some point, you have to wonder if she can go on vacation anywhere and not have it turn into a mystery!