Unethical behavior is a slippery slope, writes Mary Jo Asmus. Small transgressions might seem harmless, but they can snowball into major ethical tangles that make it harder for bosses to do their jobs effectively. "[L]oss of integrity is a silent leadership killer. ... The erosion of this value may happen very slowly over time without much notice of integrity violations on the part of those who participate in questionable practices," Asmus writes.