It Don't Mean That!
It's amazing how many people have trouble wrapping their heads around the idea that you can criticize an argument independently of whether you think the conclusion is sound. If someone says, "I believe the earth is round, because I like round things, and I like the earth!" they've presented a terrible argument. If you point that out to them, it's nonsense for them to come back with, "Ah, so you believe the earth is flat!"