I'm personally not that picky, I break up the bud pretty well though. Usually to a dust consitancy. It would usually have very tiny pecies of stem in it but whatever, their only like .1mm big. If it's for a joint ill make sure it's pure though.

My dealer takes FOREVER to break it up. We have whole conversations in the time it takes him, then by the time we smoke we can't think of anything to talk about. Seriously takes about 20 minutes per bowl. Its ridiculous