I think you would need clearer terms than good and bad to truly categorise Othello's actions.
It will be subject to your own morality as to whether you can admire and respect someone who is capable of such reprehensible deeds. As post #1 clearly argues, he is a 'great' villain - his complex plots and ability to dupe even those closest to him show the intelligence and cunning that Iago holds. However, his motivation is destruction; and we see him directly responsible for the deaths of Roderigo and Emilia, and the catalyst for those of Othello and Desdemona.
I am not sure there will ever be a definitive answer for this. Much of it is going to be dependent on how an individual perceives Iago. On one hand, it is highly evident that Iago is a malevolent force in the play. He is the reason for all the tragic events that befall upon Othello and other characters in the drama. It is his ability to manipulate others that earns him such a dubious distinction. However, it is at this point that Iago might be seen as bordering on almost "genius." Simply put, he is good at what he does. I find it difficult to find another character in literature that is as skilled as he is in making sure that others follow a plan and understanding the dynamics and nuances of individual temperament to ensure completion of a vision. It is in this realm where one could actually say that Iago is good and highly efficient in being able to set out and complete what is there. Of course, Iago's role as a villain is reprehensible, yet there is a level of admiration that one has to hold as to his possession of will to ensure that his ends are accomplished. It is here where the debate and discussion emerges and the reason why composition of a reductive answer is going to be difficult.