I am a mood reader. All the way. There is no way I'm sticking to a TBR. This is especially difficult when it comes to review copies, but that's a topic for another day.
I've always been one to resist authority and obligation. I hate being told I have to do something, or feeling like I have to. Immediately all the fun is sucked out of it. This is even true of self-imposed obligations.
For example, I seriously doubt my ability to be a productive member of a book club. Even if it was a book I really wanted to read, just knowing that there was a certain date I'd have to read it by would ruin everything and get my rebellious juices going. If I did manage to get it read, I can guarantee you it was reluctantly—no matter how good the book was.