Whenever somebody has a problem with Othello and emphasizes their displeasure by damming or insulting him, his blackness is always mentioned. It seems when somebody has to curse his name they have to curse his skin color as well. For example, Roderigo hates Othello out of jealousy for Desdemona and refers to him as a "lascivious Moor"" (Act I, scene I, line 137), which paints Othello as vulgar and sex-crazed. Brabantio, Desdemona's father, grows angry at the rumor that Othello is sleeping with his daughter. Iago describes the consequences of these acts with phrases like, "you'll have your daughter covered with a Barbary horse"" (line 122) and even, "or else the devil will make Grandsire of you"" (line 97). These descriptions make it seem like Othello and Desdemona's relationship is extremely immoral, even saying that their children would be equivalent to devil's spawn. This sentiment is even further underscored by Barbanzio's reaction, when he appeals to the Duke he accuses Othello of some sort of dark magic and says his daughter is bound "in the chains of magic"" (Act I, scene ii, line 285). Othello is essentially accused of witchcraft, with the only reasoning behind the claim being his dark complexion. The only thing that gets the Duke to acquit Othello of these allegations is his previous reputation as a soldier and leader. Without such a marvelous track record, one can assume Othello would have actually been suspected of these allegations and perhaps put to trial or even assumed guilty. In this case Othello's prowess, reputation, and usefulness in Cyprus are enough to trump the racial stereotype placed upon him, but the fact is that the accusations were only somewhat credible because of his racial identity. .
There are a multitude of other examples in which Othello's peers blame or condemn his ethnicity, but it must also be taken into account that Othello himself laments over it and at times faults it for his misfortune.