I've found that even within a single store, looking at the same model of Levi's jeans, I need to try each individual pair. I always wear the same thing: Levi's 505 34W 30L. But I find that individual specimens with this exact tag can be as much as an inch different in every dimension: waist diameter, inseam length, and even leg diameter at the hem.

So this isn't just vanity. It's also a question of horribly loose tolerances in manufacturing.