>is there any evidence that those who come to the show without prior
>radical leftist
>views (a) see in the show the features Mike describes and/or (b) are
>moved politically by the show?
Yes lots. It was widely praised for critical portrayal of the drug war by mainstream journalists who are presumably not radical leftists.
Your question makes me wonder something though. What evidence is there for your default claim that such never happens?
>How large is its audience, incidentally?
At it's peak when it was on the air about 4 1/2 million an episode. That's considerably more than Bill O'Reilly ever got. The Wire is also on dvd now so more people are seeing it that way. It works better on dvd because it's a complicated show that rewards rewinding and replaying.