What fascinates me is that two English actors who have such different accents like Idris Elba (pure South London accent) and Dominic West (plummy Public school accent) can pass for Baltimore natives; maybe I'm wrong about that but I can't recall anyone complaining about their accents in The Wire.
I have read mentions about their occasional vocal slipups not from mainstream publication commentators but from people offline and online. Their pure accents don't come out, but every now and then it sounds like a mix between the two accents and their pronunciation/accent doesn't sound like from any region in the U.S. that I know of. Baltimore accents on the show can be found in the actors who played Prop Joe, Snoop, Vice Principal Donnelly, Lieutenant Mello, and the middle school office clerk, for example.