Of course like any other stereotype, positive stereotypes can come along with a huge unseen cost attached. People who endorse stereotypes consciously or not may have some difficulty treating members of that group fairly and on an individual basis. Or they may not. People are complex after all. Just because you laugh at a joke in the abstract doesn't necessarily mean you will treat the real life object of that joke as less than. You also may remember the Pepsi Max "Love Hurts" commercial in which we saw a large black woman constantly comically assault her boyfriend/husband because he wasn't eating right. Near the end, annoyed that he smiled at a blonde white woman, she threw a can at his head, missed and hit the other woman instead. The couple then ran off.
Did you think the Haagen-Dazs Gelato commercial was humorous?