I don't remember when the "O" sticker first appeared; it's possible that it was plastered all over the cover of her first selection (which happened to be Jacquelyn Mitchard's The Deep End of the Ocean, if you were curious) and I somehow just didn't notice it. Once I did notice that sticker, I saw it everywhere, and it unnerved me. That little sticker changed the way I read. It made me self-conscious. I didn't want anyone to see me reading a novel with Oprah's seal of approval and think that I was incapable of chosing books for myself. That sticker undermined my expertise, and as much as I like Oprah, I refuse to believe that she's better at choosing books than I am. The easy fix would have been to simply peel the sticker off, but those things were made with some kind of freakishly strong Oprah-grade glue that wouldn't come off without taking a good chunk of the cover with it. So, I could look like one of Oprah's reading minions or like I don't take care of my books.
At one point, I decided that contemporary fiction was getting to be too stressful for me, so I went back to the good old classics. Of course, soon after I made this decision, Oprah stretched out a bit and started encouraging people to read Faulkner and Tolstoy and Dickens. That would have been great, except that now the sticker was gone, replaced by a permanent graphic printed right on the cover. Oprah has officially proliferated the reading world, and now she cannot be peeled away. Even your non-fiction isn't safe; if the author appeared on the Oprah show, watched the Oprah show, or has heard of Oprah, there will likely be an endorsement somewhere on the book.