On a completely unrelated note, I thought this article by John MacArthur was thought-provoking. I'll bet we could get a good discussion going on this one!
1. Innocent as to What is Evil - 1 Corinthians 14:20

2. Guilt by Association - "Rather than understanding the beliefs of a particular individual and comparing those to the Word of God, they judge the person base on the beliefs of another person. The irrationally associate the guilt of one person's poor theology onto another.
3. Honor by Association
9. Withdrawal - "...discernment does not give us license to ignore Christian fellowship and to separate ourselves from other believers."
10. Truth without Love - "Perhaps the greatest danger in discernment is that it can be done from poor motives."