From the fluffy edge of scientific research I can tell you that the belly button above will be fluff repellent. Consider the following research abstract:
"Hard facts on a soft matter! ... The hypothesis presented herein says that abdominal hair is mainly responsible for the accumulation of navel lint, which, therefore, this is a typically male phenomenon.
The abdominal hair collects fibers from cotton shirts and directs them into the navel where they are compacted to a felt-like matter. The most abundant individual mass of a piece of lint was found to be between 1.20 and 1.29 mg (n=503). However, due to several much larger pieces, the average mass was 1.82 mg in this three year study. When the abdominal hair is shaved, no more lint is collected. "
From the materials and methods: "The author first observed the accumulation of navel fluff in his early 20s. Despite thorough body hygiene including a daily morning shower, the navel filled with lint over the day. The author collected 503 pieces of navel fluff since approximately March 2005 with a total weight of almost 1 g... ...In order to investigate the role of the abdominal hair, the author also shaved his belly for this study."
Med Hypotheses. 2009 Jun;72(6):623-5. Epub 2009 Feb 23.