The way my sump is setup I have 3 sponges/filters for the water to pass through. It needs to pass through 2 of these to even reach the bioballs. The first one being in my overflow box, it collects the big stuff like poop and what-not before sending the water down into the sump. The next sponge is a large square 1 inch thick really fine thing. Only super small stuff would be able to get through it...my bioballs do not get any "detritus" on them thanks to those sponge filter things. Those filters, combined with my Live Rock and Bioballs, and snails, crabs, shrimp and other critters, and a BA protein skimmer (no not a brand), I rarely have any debris build up in my tank.
So what I'm saying is that no, my bioballs do not collect all the gunk. The things that do collect all the gunk are cleaned once a week. The bioballs handle ammonia to nitrate only, and water changes control the nitrate levels. If you have a problem with a "nitrate" factory, ease up on the feeding. Anything that isn't eaten by something will indeed fuel the nitrate factory. | 
