I have so many books I've been meaning to read recently. My problem is, I buy books in bulk, and then it takes a lot of effort to pick one to read. If I'm reading just one I'm not reading any of the others (ten points to anyone who knows which (Discworld) book I just ripped off a quote from). I've got piles and piles of brand new, shiny books all stacked in the cupboard, and there are some that I just never seem to get around to reading. I've had a pristine copy of Twilight sitting on the table next to me for the last several months, and I can never seem to find the time to open it.
Speaking of Twilight, from what I've heard (mostly, admittedly from people complaining about the fangirls) it sounds a bit like the ultimate original Sue (like Buffy). Just FYI, a Mary-Sue is a character invented to be just like the author, only perfect, and all kinds of cool things happen to her, and everyone loves her, and she's good at everything. Except, of course, in the case of Twilight, it's the readers who identify with the character and think like that. That's why I suspect it's so popular in the young adolescent age group. Bit like Harry Potter (grew out of it before the series ended :( ) or Buffy (never liked her, always preferred Cordy). And I'd just like to reiterate here that I've never even cracked the front cover open, so my judgement is, of course, completely biased and unfair. I'm sure I'll change my mind when I actually read it. Or perhaps not.
Speaking of cracking books open, I always do that. You can tell how well-read my books are from how worn the cracks in the spine are. My sister can read without doing that, and I've no idea how she does it. I just get too engrossed, and there it goes.
I think it makes them look loved. I think it adds character to a book that is in perfect condition, except for the signs of being read thoroughly and repeatedly.