the reason some jean hems pucker is because the designer used cotton thread not polly thread(industry standard). The shrinkage of the cotton in the thread causes the hem to pucker and gives it the shading we all so desire. same goes for the railroad tracks on the side seams. On the subject of authenticity you need to consider the country of origin as a major factor. Now that everybody is into their jeans not just Japanese, it is turning into a fashion trend that certain brands end up mass producing in China. Many Chinese factories have bought up the old union specials chainstitch machines from US jean factories that have gone out of business because of cheap labor overseas. Denim jeans are about American as apple pie, so if you really want to get authentic product make sure it's from a company that has always cared, not just because it's in fashion and make sure they are made in USA. Made in Japan is ok though because they care so much about their details and quality and have purchased many of Levis original 30" looms. They also have a strong passion for indigo and go to painstaking levels of dipping yarns 25 or 30 times to get that deep indigo, even going so much as to hand wringing the indigo into the yarns to get deeper indigo penitration.