I frequent a local thrift store (Deseret Industries, run by the LDS church), where I always quickly scan all 6 book shelves. Every morning (that I've been there that early), there's one dude that rushes his way to the "new" book shelves (the ones that were just rolled out of the back and not yet sorted onto the shelves), towing a cart, and he proceeds to monopolize the shelves as he roots through all the books and searches them manually on his phone (which I assume it internet-enabled).
I can't help but get a little annoyed by his presence, especially once I figured out what he was doing. He wasn't reading all those books, of course; he was hoping to make a profit on them. I, like many others, look for books to, you know, actually read, and I view this man's actions as rude. Likewise, when I offload a box or two of books to this same store, I am doing so out of a desire to give back to the local community, and it kind of chaps my hide that this asshat with his phone might buy one of my tech-related softbacks for $1 and sell it on Amazon for $5 or more, potentially denying some poor, local kid who may want to better himself by stumbling on that same book I donated.
These days, because of this leech at the thrift store, I'm more inclined to simply shred my books (they make good animal bedding and compost well) than take the effort to load them up into the car and donate them. Sure, that may be viewed as somewhat selfish, but then again, that's exactly how I view that guy who buys all the books to make a quick buck.