I was sixteen when I discovered Thomas Pynchon. It was summer, and I was within bicycling distance of the last stop of Baltimore's only subway line, so I pretty much had the run of the city despite living in the suburbs and having no car. If you know where to look, you can find a deli or soul food joint that'll sell you a mouthwatering (but artery-clogging) meal for no more than the price of a Big Mac and fries at McDonald's. Then you can head down to the Inner Harbor, park yourself on a bench with a good view and chow down while gawking at tourists from all over the globe, who have arrived not for your entertainment but for purposes of their own gawking; namely, at the sights of your hometown. If the weather's good and the eating and gawking are done, it's fun to pull a book out of your backpack and read while soaking up the sun's rays, cooled by the breeze coming off the water.
Fortunately for those who would pursue this sort of lifestyle, Baltimore is equipped with a plethora of used book stores, many of which feature paperbacks within the budget of an overgrown sixteen year old with a small income and a large appetite. It was in such a shop that I encountered an exceedingly beat-up and dog-eared edition of Gravity's Rainbow. Knowing nothing of Pynchon, I bought it partly due to its small price and partly because of some as yet unarticulated notion that old, worn-out paperback books were likely to contain good stories. I had grown up reading Ernest Hemingway from old Scribner's editions that my mom had bought new in the sixties. Hemingway was never my favorite author, but A Farewell to Arms was still a world and a half better than the shiny new Oprah-endorsed fluff that filled many of the bookshelves at home. And I had, a few years before, received a seemingly cow-trampled copy of The Hitchhiker's Guide to the Galaxy from a friend, enjoying it immensely before passing it on to someone else.
I finally understood the reason for this strange phenomenon when I had finished reading my first Pynchon novel. The best books are read from cover to cover, often several times. Of course they're going to suffer more wear and tear than second-rate texts that bore their readers, who forget and abandon them. A book that's "junk" as a physical artifact rarely, if ever, has junk printed on its pages. Beware of used books that don't look like anyone's read them.
Decrepit paperbacks have served me well. Impressed by Pynchon's work, I unearthed an old edition of V. with no front cover at a yard sale. My copy of Mason and Dixon is blighted by coffee stains. I held off reading Vineland until this year; unable to find a suitably abused copy, I unconsciously assumed no one had liked it very much.
This principle has proven useful in other settings. Two years ago I was considering buying an old Renault from a woman who had kept it in her garage for years. The paint was original and still shiny, the interior showed virtually no signs of wear, and the odometer, which she assured me was accurate, was very low for its age. The car was in showroom condition, and cheap. It ran fairly well but seemed to need a tuneup; I backed out of the deal at the last minute, on a hunch.
A month or so later, I saw it at the side of the road, its new owner kicking it in frustration. I was driving an equally old, and equally inexpensive, Volvo with cracks in the plastic dashboard and leather seats; the engine had lots of miles on it but hummed reliably without the slightest hint of a knock. It has yet to break down in the two years I've been driving it. There's a good reason you don't see many Renaults on the road nowadays. High-mileage used cars that still run well are survivors, having passed the test of long-term, regular use. Cosmetic flaws brought about by this sort of wear are actually signs of quality and durability at the mechanical and structural levels. An old car with stock parts that look like new is probably a lemon.
Shoes are another good illustration. I've got a pair of Doc Martens whose soles, after three years of use, have begun to wear through in places. A few months ago I was a bit short on cash, so I bought new shoes at Payless. Once again, there's a reason you'll never see Payless shoes with the soles worn through. Mine began falling apart at the seams after two weeks - I'd have been better off dipping into savings to buy decent shoes, and replacing that money after my next paycheck.