Answering the existential questions — what is navel fluff?

As they turn to professional careers, many scientific researchers lose the childish fascination by innate phenomena that surrounds them. And then there is The nature of navel fluff (G. Steinhauser; 2009) — a three-year, one-man study of the origins and contents of navel fluff. The author read a "popular scientific medical book," Why do Men Have Nipples?: Hundreds of Questions You'd Only Ask a Doctor After Your Third Martini (M. Leyner, B. Goldberg; 2005) and decided to have a go at answering one of the simple questions the authors of the book mentioned. Specifically, why some belly buttons accumulate more fuzz than others.
The author first observed the accumulation of navel fluff in his early twenties, despite an adequate hygiene routine, and from his observations he postulated that navel fluff is a predominantly male problem, with abdominal hair collecting fibers from shirts and transporting them into the navel via normal body movement. He collected over five hundred specimens of his own navel fluff through a period of three years. In case you were wondering, they weighed almost 1 gram in total, and the lint had the color of the shirts that he was wearing, supporting his hypothesis. Additionally, the most navel fluff was produced when wearing new, cotton T-shirts. For science, he proceeded to confirm this result by shaving his abdominal hair, whereupon he provided us with photos, a mass distribution of the extracted fluff, and feedback from his hairy and non-hairy male friends.
One fascinating piece of information that he used is that cotton lint acts as a good adsorbent, collecting supstances such as dust, cutaneous scales, fat, protein, and sweat, thus making him postulate that individuals who find more navel fluff also have cleaner belly buttons. He proceeded to support the claim with a personal account of having to clean his belly button more thoroughly in his youth. The paper ends in a summary and a victorious winking smiley face, as he finally managed to answer the simple question of the nature of navel fluff, aiding general medical practicioners across the globe. For the navel fluff enthusiast, check out the story on Another matter: Navel fluff, published in Nature in 1997.