A sound editor who worked on the Wire did an AMA over at Reddit; Kottke has highlights but this is my favorite:

McNulty (Dom West) came in often and was awesome, as well. His accent showed most often when the character was drunk or angry. Oddly, the name “Stringer Bell” tripped him up a lot. “Stringa” and then a very over-enunciated end to “Bell-eh.” Also, the words “fuck” and “cunt” came out “feck” and “cahnt” and the only way to break him of it was to stand right in front of him (so he could watch the mouth shape) and say the word over and over again. So a Dom West ADR session often went like this:

Me (with Dom staring at my mouth): Cunt. Cunt. Cunt.
Dom: Cahnt. Shit, do it again, please.
Me: Cunt. Cunt. Cunt.
Dom: Cunt. Cunt. OK, let’s record…
(three beeps, the line starts and):
Dom: …cahnt. Feck! Say it again.
Me: Cunt….