One of the best examples of a real Australian accent I've heard on American television is Dr. Chase [Jesse Spencer] from House, who is a real Australian and did not ham it up for an American audience. (Oddly though, the man who played his father in one episode had possibly the most embarrassingly bad fake Australian accent ever. Surprised Spencer didn't kick his arse during filming.)
You do not get real foreign accents on prime time American television, the viewers would be bemused and look for subtitles.
You get what Americans think are foreign accents, i.e. lightly accented. The one exception is that Brits playing bad guys are allowed to use camp, pantomime villain accents. Alan Rickman has made his fame and fortune from this, a shame as he is rather a good actor.
Hugh Grant sounds nothing like he does/did before that series started.
One of the best examples of a real Australian accent I've heard on American television is Dr. Chase [Jesse Spencer] from House, who is a real Australian and did not ham it up for an American audience. (Oddly though, the man who played his father in one episode had possibly the most embarrassingly bad fake Australian accent ever. Surprised Spencer didn't kick his arse during filming.)