"Not I for this fair island. I do love Cassio well and would do much To cure him of this evil-" - Iago
 In this quote Iago is pretending to be a nice guy by both pointing the blame of evil on another, in this case Cassio as well as by making himself seem like a loving guy. This kind of  messing with people and beating around the bush proves that Iago is more than just a jerk, but actually evil.