See also:
...ad nauseam. While I appreciate the efforts of any minority to see themselves accurately represented in popular television programming, I think their efforts are fundamentally flawed for two reasons.
First, there is no "accurate representation" of an entire group. If you're expecting a show featuring a handful of characters to provide a representative cross section of an entire minority in just half an hour per week, you're fighting a lost cause. One character will not, cannot, stand in for an entire group of thousands or millions of people. He'd never be able to stop talking, for one thing.
Second, you're talking about television here. TV is entertainment for the masses. The characters on a sitcom are, first and foremost, supposed to be funny. The writers are always going to play up the stereotypes toward that end, regardless of their relevance, for as long as it gets them laughs. If you're demanding intelligent production from the majority of your TV shows, you should stop complaining about sitcoms and spend your time promoting PBS instead.
I understand that it's great when certain shows provide "good" stereotypes of your favorite minority, and that it's uncomfortable when other shows provide "bad" stereotypes. But the media has been earning its entertainment dollars by capitalizing on stereotypes since the dawn of the electronic age, and it hasn't stopped yet. As long as the joke gets laughs, they'll keep it going in reruns.
And if the stereotyping gets too much in the way of your enjoyment, just do what I did: kill your television.