I was over at A Wrinkle in Thyme Farm last week carding out some fleece and chatting with my sheep mentors. Fleece is always part of the conversation! Anyway, I asked how the big yarn mills get all the vegetable matter out of the fleece. Marty said they use chemicals! What?? Yes, chemicals. They call it "carbonization". They put acid in the wool which degrades the veg (straw, hay chaff, that kind of stuff) then they dry the wool, shake out the "carbon" and re-rinse the wool in other chemicals that neutralize the acid. Seriously! These chemicals are what most people are allergic to. I couldn't believe it. No, yes, I can believe it. So you think when you buy 100% natural wool, be it sheep, alpaca, or mohair, that it's natural. Not so much.
What it boils down to is yes, there are some little bits of veg in my fleece. Now, if you want perfect fleece, I can send it off to a huge mill somewhere and they can treat it with chemicals that may affect your skin. Or, you can accept some imperfection in small farm fleeces (Fleeces? Is that a word?). Some will come out when when you draft and spin. If I send it to a small, natural mill, even more will come out because they card multiple times before spinning but not use chemicals.
Here is a great article about fleece as a wearable. It spells out the pluses of fleece and the negatives about chemically treated fleece.