When people watch "The Colbert Report," for example, most of them realize that it is a "spoof" of conservative opinions shows like The O'ReillyFactor, and therefore anything Stephen Colbert says is taken as a joke. But what about people who don't understand the premise of the show? Colbert spends a full half-hour pretending to be a radical Republican with some really extreme viewpoints, but what if people don't get it?
That's what happened recently with The New Yorker, according to this NPR article. This past July, The New Yorker used this cartoon as its cover art:

Ideally, satire is intended to bring about improvement by means of pointing out a flaw in society (such as the racism and ignorance depicted above) but sometimes it serves the opposite purpose and reinforces negative stereotypes.
Where does the media draw the line? I think the answer is that they use their best judgment and sometimes get it wrong. Luckily, for publications like The New Yorker, they just wait a week and put something new, and less offensive out in their next issue. They get a little bad press and move on, but at what cost to the people fighting against these stereotypes?