Good guys and bad guys

Ann and I went to see a movie which, honestly, was so gross that I didn't enjoy it at all -- The Black Dahlia. I am NOT recommending it to anyone. Post facto, I wanted to see what Plugged In would say about it. Overall, I agreed with the review, but I didn't understand this remark:

Other Negative Elements
As is the norm with noir thrillers, several police detectives are revealed to be corrupt and/or compromised, muddying the lines between the good guys and the bad guys...

Um... excuse me but isn't it...um...TRUE....that many officials are corrupt? The hero/villian distinction makes movies like Spiderman and The Matrix unrealistic, thereby giving viewers a skewed perception of the world. Film Noir's realism, even if it is not enjoyable, is at least truthful. That's not a negative element. While I don't think there is a need for graphic sex and violence, portraying all people as sinful is...dare I say it...BIBLICAL?