I cull all my seeds/nuts/grains to pick out the 4 Ds: Decayed, Discolored, Dented, and Dwarfed. I always find lots of decayed seeds/grains and foreign objects when I cull, no matter whether they are purchased from bulk(WholeFoods) or reputable retailors (sunorganics.com, sproutspeople.com). However, because seeds, such as flax and sesame, are so small, I spend 80% of my food preparation culling when I have to use them(I actually go through almost every one of them).
Do you cull? Does it take you this long time?